57 results on '"Yugandhar Bitla"'
Search Results
2. Structural, optical and dielectric investigations on RECr0.85Mn0.15O3 (RE = Ho, Gd and Pr) nanoparticles
- Author
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Komal Kanwar, Sonali Pradhan, S. Satapathy, Yugandhar Bitla, and Neeraj Panwar
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Geochemistry and Petrology ,General Chemistry - Published
- 2023
3. Flexible magnetoelectric complex oxide heterostructures on muscovite for proximity sensor
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Yong-Jyun Wang, Jia-Wei Chen, Yu-Hong Lai, Pao-Wen Shao, Yugandhar Bitla, Yi-Chun Chen, and Ying-Hao Chu
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General Materials Science ,Electrical and Electronic Engineering - Abstract
In modern technology, recent advances in multi-functional devices are rapidly developed for the diverse demands of human beings. Meanwhile, durability and adaptability to extreme environmental conditions are also required. In this study, a flexible magnetoelectric (ME) heterostructure based on CoFe2O4/Pb(Zr,Ti)O3 composite thin film on muscovite is presented, with two geometries of the constituents, namely laminar heterostructure, and vertical nanostructure, adopted for the comparison. On the other hand, credited to the mechanical flexibility of muscovite, the impact of flexibility on ME properties is also discussed with a series of bending tests. Moreover, the ME response sustains for 10,000 times bending without significant decrease, validating the mechanical durability of this heterostructure on muscovite. With these advantages, a flexible proximity sensor based on this heterostructure is demonstrated for motion detection. It is expected to offer a pathway for creating the next-generational flexible devices, showing potential for future practical application.
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- 2023
4. Enhancing the ultraviolet photosensing properties of nickel oxide thin films by Zn–La co-doping
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Ramesh Ade, V. Ganesh, I.S. Yahia, P. Mohanraj, I. Loyola Poul Raj, S. Valanarasu, and Yugandhar Bitla
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Materials science ,Photoluminescence ,Band gap ,Process Chemistry and Technology ,Nickel oxide ,Doping ,Non-blocking I/O ,Analytical chemistry ,Oxide ,Crystal structure ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,Ceramics and Composites ,Thin film - Abstract
In this work, co-doping effects of transition (Zn) and rare-earth (La) elements on the crystalline structure, surface morphology, photoluminescence, optical and photosensing properties of NiO thin films are studied. NiO, NiO:Zn(1%), NiO:La(1%), and NiO:Zn(1%):La(1%) thin films are fabricated using the nebulizer spray pyrolysis (NSP) method. X-ray diffraction study revealed the cubic NiO structure of all the films. Photoluminescence (PL) spectra of thin films exhibit various emission peaks centered at the wavelengths of 387, 414, 437, 451, 477, and 521 nm. The optical bandgap energy (Eg) values are found to be 3.46, 3.43, 3.39 and 3.33 eV for NiO, NiO:Zn(1%), NiO:La(1%) and NiO:Zn(1%):La(1%) thin films, respectively. The fabricated (Zn, La) co-doped NiO i.e., NiO:Zn(1%):La(1%) photo-detector exhibits highest responsivity (R), external quantum efficiency (EQE) and detectivity (D*) values of 0.50AW-1, 169% and 14.5 × 109 Jones, respectively as compared to NiO, NiO:Zn(1%) and NiO:La(1%) photo-detectors. The present study revealed that the transition and rare-earth elements co-doping can be an effective approach for tuning the various physical properties of semiconducting oxide films.
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- 2022
5. Large Low-Magnetic-Field Magnetocapacitance Effect and Spin Accumulation in Graphene Oxide
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R. S. Joshi, Bhavani Kori, S R Singh, Bhagyashri Hiremath, K Santosh Kumar, Yugandhar Bitla, and Mallikarjun Rampur
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chemistry.chemical_compound ,Materials science ,Condensed matter physics ,chemistry ,Graphene ,law ,Low magnetic field ,Oxide ,Magnetocapacitance ,Electrical and Electronic Engineering ,Electronic, Optical and Magnetic Materials ,law.invention ,Spin-½ - Published
- 2022
6. Highly sensitive hexagonal-shaped ZnS–Cu thin films for photo-detector applications
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A. Jesu Jebathew, M. Karunakaran, Ramesh Ade, Joice Sophia Ponraj, V. Ganesh, Rajesh Kumar Manavalan, Yugandhar Bitla, I. S. Yahia, and H. Algarni
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Electrical and Electronic Engineering ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Published
- 2022
7. Barium hexaferrite/muscovite heteroepitaxy with mechanically robust perpendicular magnetic anisotropy
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Wei-En Ke, Pao-Wen Shao, Chang-Yang Kuo, Haili Song, Rong Huang, Naoki Yagi, Tsuyoshi Kimura, Yugandhar Bitla, Chun-Fu Chang, and Ying-Hao Chu
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TK7800-8360 ,TA401-492 ,General Materials Science ,Electrical and Electronic Engineering ,Electronics ,Materials of engineering and construction. Mechanics of materials - Abstract
Recent advances in the design and development of magnetic storage devices have led to an enormous interest in materials with perpendicular magnetic anisotropy (PMA) property. The past decade has witnessed a huge growth in the development of flexible devices such as displays, circuit boards, batteries, memories, etc. since they have gradually made an impact on people’s lives. Thus, the integration of PMA materials with flexible substrates can benefit the development of flexible magnetic devices. In this study, we developed a heteroepitaxy of BaFe12O19 (BaM)/muscovite which displays both mechanical flexibility and PMA property. The particular PMA property was characterized by vibrating sample magnetometer, magnetic force microscopy, and x-ray absorption spectroscopy. To quantify the PMA property of the system, the intrinsic magnetic anisotropy energy density of ~2.83 Merg cm−3 was obtained. Furthermore, the heterostructure exhibits robust PMA property against severe mechanical bending. The findings of this study on the BaM/muscovite heteroepitaxy have several important implications for research in next-generation flexible magnetic recording devices and actuators.
- Published
- 2021
8. Enhanced optoelectronic properties of Ti-doped ZnO nanorods for photodetector applications
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I.S. Yahia, Subodh Kumar, Ramesh Ade, Sudershan Kumar, Yugandhar Bitla, S. Sasikumar, S. Valanarasu, Hamed Algarni, and V. Ganesh
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Materials science ,Photoluminescence ,business.industry ,Scanning electron microscope ,Process Chemistry and Technology ,Photoconductivity ,Doping ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Materials Chemistry ,Ceramics and Composites ,Optoelectronics ,Quantum efficiency ,Nanorod ,Thin film ,business ,Wurtzite crystal structure - Abstract
We report the effect of Ti-doping on structural, morphological, photoluminescence, optical and photoconductive properties of ZnO thin films. Pure and Ti(1, 3 and 5%)-doped ZnO thin films are deposited by the successive ionic layer adsorption and reaction (SILAR) method. The X-ray diffraction analysis revealed the single-phase hexagonal wurtzite ZnO structure of all the films. Scanning electron microscope images suggest the formation of rod shaped particles in Ti-doped ZnO thin films. Photoluminescence spectra of all the films show emission peaks centered at 398 nm, 413 nm, 438 nm, 477 nm and 522 nm wavelengths. Optical properties support the semiconducting nature of all the films. The optical bandgap values are estimated to be 3.29 eV, 3.26 eV, 3.19 eV and 3.23 eV for ZnO, ZnO:Ti(1%), ZnO:Ti(3%) and ZnO:Ti(5%) thin films, respectively. Photoconductivity study indicates that ZnO:Ti(3%) thin film exhibits high responsivity, external quantum efficiency and detectivity of 0.30 AW-1, 97% and 5.49 × 1010 Jones, respectively, among all the films. The enhanced photoconductivity of Ti-doped ZnO thin films make them useful for optoelectronic applications.
- Published
- 2021
9. Structural, magnetic and electrical transport properties of the sol-gel derived La1-xCaxMnO3 (0≤x≤0.3) nanoparticles
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P.V. Jithin, Yugandhar Bitla, Manju Mishra Patidar, V. Ganesan, K.J. Sankaran, and Joji Kurian
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General Materials Science ,Condensed Matter Physics - Published
- 2023
10. Fabrication of Cost-Effective Nebulizer Sprayed In2S3 Thin Films for Photodetector Applications
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V. Ganesh, M. Ramudu, I.S. Yahia, A. Vimala Juliet, M. Dharani Devi, Yugandhar Bitla, and R. S. Rimal Isaac
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010302 applied physics ,Fabrication ,Materials science ,business.industry ,Band gap ,chemistry.chemical_element ,Photodetector ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Responsivity ,chemistry ,0103 physical sciences ,Materials Chemistry ,Optoelectronics ,Quantum efficiency ,Electrical and Electronic Engineering ,Thin film ,0210 nano-technology ,business ,Indium ,Visible spectrum - Abstract
The present study investigates the effect of precursor solution volume on the structural, morphological, compositional, optical, and electrical properties of In2S3 films. Thin films of In2S3 were deposited by a nebulizer spray pyrolysis technique on glass substrates with varying precursor solution volumes (4 mL, 8 mL, 12 mL, and 16 mL). X-ray diffraction studies confirmed the formation of the tetragonal phase and the compositional studies using energy-dispersive x-ray spectra showed the presence of only indium and sulfur. The energy bandgap of the films was found to be in the range of 2.51–2.4 eV. The I-V characteristics and photoresponses of the photodetectors including photosensitivity, responsivity, and detectivity were evaluated under visible light illumination. Enhanced photo-responsivity was observed with an increase in the precursor solution volume, with a maximum value of 0.213 AW−1 observed for the thin film coated with 12 mL precursor solution volume. For the thin film coated with a volume of 12 mL precursor solution, external quantum efficiency of 69% and detectivity of 20 × 109 Jones were observed. This In2S3 thin film may find application in the fabrication of efficient and cost-effective photodetector devices.
- Published
- 2021
11. Optoelectronic properties of spray pyrolyzed NiO:Pr thin films
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Ramesh Ade, V. Ganesh, Yugandhar Bitla, and Y. Vijaya Kumar
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General Materials Science ,General Chemistry - Published
- 2022
12. Facile fabrication and characterization of nanostructured Y:CdO thin films
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S. AlFaify, Mohd. Shkir, V. Ganesh, Yugandhar Bitla, and L. Haritha
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inorganic chemicals ,Fabrication ,Materials science ,genetic structures ,Band gap ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Biomaterials ,Condensed Matter::Materials Science ,chemistry.chemical_compound ,Condensed Matter::Superconductivity ,Materials Chemistry ,Thin film ,Spin coating ,business.industry ,Doping ,technology, industry, and agriculture ,General Chemistry ,Yttrium ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,eye diseases ,Grain size ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,chemistry ,Ceramics and Composites ,Cadmium oxide ,Optoelectronics ,Condensed Matter::Strongly Correlated Electrons ,sense organs ,0210 nano-technology ,business - Abstract
Cadmium oxide (CdO) thin films doped with different yttrium (Y) concentrations have been prepared by the cost-effective spin coating technique. The effect of Y doping on structural, morphological, linear, and nonlinear optical properties of the as-prepared CdO thin films is studied. The AFM morphology of the thin films revealed grain size increase with the increase in the percentage of Y doping. From the optical properties, it is found that the films are highly transparent and the optical band gap spreads over the range of 2.3–2.8 eV. The Y doping drastically suppresses the linear and nonlinear optical properties.
- Published
- 2021
13. Structural, Optical and Dielectric Properties of Nd Doped NiO Thin Films Deposited with a Spray Pyrolysis Method
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S. AlFaify, B. Ravi Kumar, Yugandhar Bitla, V. Ganesh, and I.S. Yahia
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Materials science ,Polymers and Plastics ,Absorption spectroscopy ,Band gap ,Doping ,Non-blocking I/O ,Analytical chemistry ,02 engineering and technology ,Dielectric ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Materials Chemistry ,Direct and indirect band gaps ,Thin film ,0210 nano-technology ,Refractive index - Abstract
The effect of Nd doping (1, 3 and 5 wt%) on the structural, morphological, electrical and optical properties of NiO thin films deposited on glass substrates using nebulizer spray pyrolysis method are investigated. The X-ray diffraction study reveals cubic structure with an improvement in crystallinity upon the incorporation of Nd into NiO lattice. The films are > 50% transparent in the high wavelength region. The absorption spectra witnesses a sharp fall in the wavelength range, 300 nm
- Published
- 2021
14. Bulk-surface coupling in dual topological insulator Bi1Te1 and Sb-doped Bi1Te1 single crystals via electron-phonon interaction
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Shoubhik Mandal, Debarghya Mallick, Yugandhar Bitla, R Ganesan, and P S Anil Kumar
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General Materials Science ,Condensed Matter Physics - Abstract
Recently, B i 1 T e 1 has been proved to be a dual topological insulator (TI), a new subclass of symmetry-protected topological phases, and predicted to be higher order topological insulator (HOTI). Being a dual TI (DTI), Bi1Te1 is said to host quasi-1D surface states (SSs) due to weak TI phase and topological crystalline insulating SSs at the same time. On the other hand, HOTI supports topologically protected hinge states. So, B i 1 T e 1 is a unique platform to study the electrical signature of topological SS (TSS) of fundamentally different origins. Though there is a report of magneto-transport measurements on large-scale Bi1Te1 thin films, the Bi1Te1 single crystal is not studied experimentally to date. Even the doping effect in a DTI Bi1Te1 is missing in the literature. In this regard, we performed the perpendicular and parallel field magneto-transport measurement on the exfoliated microflake of Bi1Te1 and Sb-doped Bi1Te1 single crystals, grown by the modified Bridgmann method. Our metallic sample shows the weak anti-localization behavior analyzed by the multi-channel Hikami-Larkin-Nagaoka equation. We observed the presence of a pair of decoupled TSS. Further, we extracted the dephasing index (β) from temperature (T)-dependence of phase coherence length (L ϕ ), following the power law equation (L ϕ ∝ T − β ). The thickness-dependent value of β indicates the transition in the dephasing mechanism from electron-electron to electron-phonon interaction with the increase in thickness, indicating the enhancement in the strength of bulk-surface coupling. Sb-doped system shows weakened bulk-surface coupling, hinted by the reduced dephasing indices.
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- 2023
15. In-field critical behaviour of β-Mn type Co7Zn7Mn6 skyrmion-host
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null Pardeep, Yugandhar Bitla, null Lalita, Ajit Kumar Patra, and G.A. Basheed
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Electrical and Electronic Engineering ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Published
- 2023
16. Chiral-fluctuations mediated helical to paramagnetic phase transition and scaling study in β-Mn type Co8Zn8Mn4 chiral magnet
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null Pardeep, null Lalita, Yugandhar Bitla, Sujoy Saha, Ajit Kumar Patra, and G A Basheed
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General Materials Science ,Condensed Matter Physics - Abstract
We report detailed magnetization and ac susceptibility studies on a chiral cubic β-Mn type Co8Zn8Mn4 alloy near the onset of magnetic ordering temperature. The Co8Zn8Mn4 alloy undergoes a complex series of temperature-driven transition from paramagnetic (PM) to helimagnetic phase through an intermediate inhomogeneous chiral fluctuations phase. The Gaussian shaped peak in χ ′ ( T , H = 0 Oe) at T H M ≅ 343.19 K is analogous to that of the zero-field transition to long-period modulated helical state. Moreover, a pronounced field-induced anomaly in χ ′ (T, H ⩾ 500 Oe) rises quickly with field above T H M like a fingerprint, evident of a field-induced crossover into a precursor region. The in-field critical behavior characterizing a ferromagnetic-PM phase transition in the vicinity of ordering temperature confirms that Co8Zn8Mn4 chiral magnet belongs to the 3D-Heisenberg universality class. The existence of precursor region and the sizable expansion in the transition temperature, T C can be explained by the Landau equation.
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- 2023
17. Effects of surface polarity on the structure and magnetic properties of epitaxial h-YMnO3 thin films grown on MgO substrates
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Tahta Amrillah, My Ngoc Duong, Yu-Xun Chen, Yugandhar Bitla, Malik Anjelh Baqiya, Fitri Nur Indah Sari, Le Thi Quynh, Angga Hermawan, Firman Mangasa Simanjuntak, Chia-Hao Chen, Kaung-Hsiung Wu, and Jenh-Yih Juang
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Materials Chemistry ,Electrochemistry ,Electronic, Optical and Magnetic Materials - Abstract
YMnO3 (YMO) thin film is one of the highly studied multiferroic materials due to its tunable crystalline structure via misfit strain from the substrate. This tunability involves intriguing physical phenomena that encourage further explorations for fundamental research and practical applications. The configuration of the initial atomic layers during the growth of YMO thin films plays a key role in determining their physical properties. In the present research, the correlation between the substrate’s polarity and the misfit strain of the YMO films is studied comprehensively. The results showed that despite the YMO films grown on MgO (100) and MgO (111) being under the same growth conditions and having resulted in the same hexagonal crystal structure (h-YMO), the films do exhibit distinctly different microstructures, electronic structures, and magnetic properties. We suggest that the extent of charge accumulation induced by the surface polarity of the substrates may have resulted in a substantially different intermixing feature at the h-YMO/substrate interfaces, which, in turn, alters the structure and thus the physical properties of the films. Our results open up the possibility of manipulating the h-YMO thin film’s magnetic properties by interfacial engineering without significantly altering the structure of the films which could benefit the fabrication efficiency for various next-generation electronics.
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- 2022
18. Studies of the Effect of Bi-Doped on Structural, Electrical, Optical Properties of Spin-Coated Sno2 Transparent Conducting Oxide Thin Films
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Harish Sharma Sharma Akkera, Peddavarapu Sivakumar, Nagaiah Kambhala, T. Ranjeth Kumar Reddy, G. Srinivas Reddy, and Yugandhar Bitla
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- 2022
19. Possible Evolution of Griffiths-Like Phase in Nano-Sized La1-Xcaxmno3
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Jithin P. V, Yugandhar Bitla, M. Mishra Patidar, V. Ganesan, Sankaran K. J, and Joji Kurian
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History ,Polymers and Plastics ,Business and International Management ,Industrial and Manufacturing Engineering - Published
- 2022
20. Structural, electrical, and optical properties of rare-earth Sm3+ doped SnO2 transparent conducting oxide thin films for optoelectronic device applications: Synthesized by the spin coating method
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Harish Sharma Akkera, Yathish Kumar, M. Dilip Kumar, G. Srinivas Reddy, B. Ravi Kumar, U. Mahaboob Pasha, Yugandhar Bitla, and V. Ganesh
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Inorganic Chemistry ,Organic Chemistry ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Atomic and Molecular Physics, and Optics ,Spectroscopy ,Electronic, Optical and Magnetic Materials - Published
- 2022
21. Improvement in photo-device properties of CuO thin films for opto-electronic applications: effects of (Ni, Co) co-doping
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T Gnanasekar, S Valanarasu, Ramesh Ade, A Vimala Juliet, V Ganesh, T H AlAbdulaal, and Yugandhar Bitla
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Condensed Matter Physics ,Mathematical Physics ,Atomic and Molecular Physics, and Optics - Abstract
We report co-doping effects of transition metal elements (Ni, Co) primarily on the opto-electronic properties of CuO thin films. CuO, CuO:Ni(1%), CuO:Co(1%) and CuO:Ni(1%):Co(1%) thin films were deposited via the spray pyrolysis route. Structural studies revealed the monoclinic CuO structure for all films. For all the films scanning electron microscope (SEM) images showed a crack-free and homogeneous surface. Photoluminescence (PL) spectra of all the films exhibited four emission peaks at 415, 451, 477, and 521 nm wavelengths. The optical bandgap (E g) values were around 2.12 eV, 2.18 eV, 2.05 eV and 1.84 eV for CuO, CuO:Ni(1%), CuO:Co(1%) and CuO:Ni(1%):Co(1%)thin films, respectively. CuO:Ni(1%):Co(1%) photo-device displayed a large responsivity (R) of 0.43 AW−1, external quantum efficiency (EQE) of 100% and detectivity (D *) of 9.55 × 109 Jones. Hence, co-doping of transition metal elements would be one of the effective approaches for enhancing opto-electronic properties of metal oxide compounds.
- Published
- 2022
22. Corrigendum to 'Enhancement in optoelectronic properties of europium-doped ZnS thin films prepared by nebulizer spray technique for UV photodetection applications' [Mater. Sci. Semicond. Process. (2022) 106572]
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M. Dharani Devi, A. Vimala Juliet, Ramesh Ade, M. Thirumoorthi, P. Diana, S. Saravanakumar, V. Ganesh, Yugandhar Bitla, and H. Algarni
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Mechanics of Materials ,Mechanical Engineering ,General Materials Science ,Condensed Matter Physics - Published
- 2022
23. Structural, electrical, and optical properties of spin-coated Bi:SnO2 transparent conducting oxide thin films
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Harish Sharma Akkera, Peddavarapu Sivakumar, Yugandhar Bitla, Ganesh Vanga, Nagaiah Kambhala, C.S. Naveen, T. Ranjeth Kumar Reddy, and G. Srinivas Reddy
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Electrical and Electronic Engineering ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Published
- 2022
24. van der Waals heteroepitaxy on muscovite
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Yugandhar Bitla, Ying-Hao Chu, and Min Yen
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chemistry.chemical_classification ,Materials science ,Muscovite ,Soft Technology ,Material system ,02 engineering and technology ,Polymer ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Engineering physics ,0104 chemical sciences ,symbols.namesake ,chemistry ,Mechanical stability ,symbols ,engineering ,General Materials Science ,Electronics ,van der Waals force ,0210 nano-technology ,Short duration - Abstract
As current electronics makes a transition from bulky and rigid templates to lightweight and flexible ones, the emerging field of soft technology is set to revolutionize our daily life. Currently, polymer based templates dominate this field due to their excellent mechanical characteristics and low cost, but limited thermal budget and stabilities are the major technological bottlenecks resulting in poor performance and short duration of lifetime. Recently, the technology based on van der Waals heteroepitaxy on muscovite is considered as a promising solution to overcome these barriers at once. In this paper, the characteristics of muscovite and the mechanism of van der Waals heteroepitaxy will be introduced, after that, a variety of materials on muscovite via van der Waals heteroepitaxy and the efforts on practical applications are reported. With the outlook of material science and help of advanced measurements, the evidence of heteroepitaxy of muscovite and overlayers has been deeply analyzed. Moreover, various measurements of properties was carried under bending conditions to demonstrate the mechanical stability and reliability. Through this review, we pave the path to develop more material systems on muscovite to make MICAtronics completely.
- Published
- 2019
25. Evaluation of temperature dependent electrical transport parameters in Fe3O4/SiO2/n-Si metal–insulator-semiconductor (MIS) type Schottky barrier heterojunction in a wide temperature range
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Yugandhar Bitla, Kesarla Mohan Kumar, Srinivas Godavarthi, N. Nanda Kumar Reddy, Venkata Krishnaiah Kummara, V. Manjunath, Harish Sharma Akkera, S. A. K. Jilani, and S.V. Prabhakar Vattikuti
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010302 applied physics ,Materials science ,Condensed matter physics ,Equivalent series resistance ,business.industry ,Schottky barrier ,Thermionic emission ,Heterojunction ,Atmospheric temperature range ,Sputter deposition ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Semiconductor ,0103 physical sciences ,Electrical and Electronic Engineering ,business ,Diode - Abstract
In this manuscript, we reported the electrical characteristics and structural analysis of In/Fe3O4/SiO2/n-Si/In MIS-type SBD heterostructure comprehensively in the temperature range 10–300 K using I–V, XRD, TEM and AFM measurements. Pulsed laser deposition in association with DC magnetron sputtering techniques has been utilized to fabricate the proposed In/Fe3O4/SiO2/n-Si/In heterojunction. The fabricated heterojunction revealed that the I–V curves are non-linear and asymmetric in nature. Using these I–V curves in the forward-bias region, SBH is calculated as 0.02 eV at 10 K and 0.74 eV at 300 K. On the other hand, the ideality factor (n) value was calculated as 7.55 at 10 K and 1.37 at 300 K. The series resistance (RS) values were also evaluated using Chenug’s method and the values were 1121 Ω at 10 K and 334 Ω at 300 K. The dependence of important diode parameters such as SBH, ‘n’ and ‘RS’ on measurement temperature was effectively explained firstly on account of triple Gaussian distribution of barrier heights with the help of barrier inhomogeneities of the prepared heterojunction. The value of the Richardson’s constant calculated for the fabricated In/Fe3O4/SiO2/n-Si/In heterojunction in the 110–300 K temperature regime was calculated to be 115.26 A/cm2K2 and is approximately equal to the theoretical value of 120 A/cm2K2 for n-type Si. In addition, the higher value (greater than one) of ideality factor at all operating temperatures from 10–300 K demonstrated that the probable current transport across the Fe3O4/SiO2/n-Si junction is not only due to the thermionic emission (TE) mechanism. Hence, to reveal the origin of current transport mechanism i.e., other than TE, we noticed that the governing current transport process through the fabricated hetrojunction is mainly due to the tunneling assisted Poole–Frenkel class of emission across the Fe3O4/SiO2/n-Si junction which is found to be temperature-dependent.
- Published
- 2019
26. Effect of Gd doping on spray pyrolyzed NiO thin films for optoelectronic applications
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V. Ganesh, Harish Sharma Akkera, Yugandhar Bitla, L. Haritha, S. AlFaify, and I.S. Yahia
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Electrical and Electronic Engineering ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Published
- 2022
27. Enhancement in optoelectronic properties of europium-doped ZnS thin films prepared by nebulizer spray technique for UV photodetection applications
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M. Dharani Devi, A. Vimala Juliet, Ramesh Ade, M. Thirumoorthi, P. Diana, S. Saravanakumar, V. Ganesh, Yugandhar Bitla, and H. Algarni
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Mechanics of Materials ,Mechanical Engineering ,General Materials Science ,Condensed Matter Physics - Published
- 2022
28. Evidence for canonical spin glass behaviour in polycrystalline Mn1.5Fe1.5Al Heusler alloy
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Alexey V. Lukoyanov, Yugandhar Bitla, E. I. Shreder, Shubhra Dash, Abhinav Kumar Khorwal, Ajit K. Patra, Nancy, M. Vasundhara, and Arun Kumar
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Materials science ,Spin glass ,Condensed matter physics ,media_common.quotation_subject ,Frustration ,Coercivity ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Magnetization ,Exchange bias ,Remanence ,Antiferromagnetism ,Ground state ,media_common - Abstract
Magnetic properties of magnetically frustrated polycrystalline Mn1.5Fe1.5Al Heusler type alloy with a β-Mn structure were systematically studied using dc magnetization, ac susceptibility, magnetic relaxation and magnetic memory effect measurements to understand its magnetic ground state. The Mn1.5Fe1.5Al alloy system exhibits a sharp peak at low temperature around 34.5 K with strong antiferromagnetic correlations ( θ CW ∼ −639 K) and a high degree of frustration ( f p ∼ 18.7) which suggest the presence of competing magnetic interactions. Despite of strong antiferromagnetic correlations, this peak has spin-glass character as confirmed by the observations of bifurcation of the zero-field-cooled and field-cooled magnetization curves below the irreversibility temperature, field dependent shift of the irreversibility temperature, unidirectional exchange bias effect on the field-cooled M-H hysteresis loop, exponential decay of the temperature variation of remanence and coercivity, frequency dependent shift of the spin glass freezing temperature (Tf) as per the dynamic scaling laws given by the critical slowing down model and Vogel-Fulcher law, magnetic relaxation and magnetic memory effect below Tf. The observation of a clear asymmetric response with respect to the temperature cycling in the magnetic relaxation measurements validates the hierarchical model of the spin-glass magnetic relaxation in Mn1.5Fe1.5Al alloy. Since the behaviour exhibited by the Mn1.5Fe1.5Al alloy has perfect similarity with the well-known atomic spin glasses like CuMn, AuFe, therefore, it may be considered as canonical spin-glass system.
- Published
- 2022
29. The role of silver doping in tuning the optical absorption, energy gap, photoluminescence properties of NiO thin films for UV photosensor applications
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I. Loyola Poul Raj, S. Valanarasu, R.S. Rimal Isaac, M. Ramudu, Yugandhar Bitla, V. Ganesh, and I.S. Yahia
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Electrical and Electronic Engineering ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Published
- 2022
30. Low-Temperature Magnetic and Magnetocaloric Properties of Manganese-Substituted Gd0.5Er0.5CrO3 Orthochromites
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Neeraj Panwar, Kuldeep Singh, Komal Kanwar, Yugandhar Bitla, Surendra Kumar, and Venkata Sreenivas Puli
- Subjects
Inorganic Chemistry ,General Chemical Engineering ,General Materials Science ,Condensed Matter Physics ,rare-earth orthochromites ,magnetization reversal ,magnetocaloric effect - Abstract
Rare-earth chromites have been envisioned to replace gas-based refrigeration technology because of their promising magnetocaloric properties at low temperatures, especially in the liquid helium temperature range. Here, we report the low-temperature magnetic and magnetocaloric properties of Gd0.5Er0.5Cr1−xMnxO3 (x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) rare-earth orthochromites. The Néel transition temperature (TN) was suppressed from 144 K for Gd0.5Er0.5CrO3 to 66 K for the Gd0.5Er0.5Cr0.5Mn0.5O3 compound. Furthermore, magnetization reversal was observed in the magnetization versus temperature behavior of the Gd0.5Er0.5Cr0.6Mn0.4O3 and Gd0.5Er0.5Cr0.5Mn0.5O3 compounds at 100 Oe applied magnetic field. The magnetic entropy change (−∆S) value varied from 16.74 J/kg-K to 7.46 J/kg-K, whereas the relative cooling power (RCP) ranged from 375.94 J/kg to 220.22 J/kg with a Mn ion concentration at 5 T field and around 7.5 K temperature. The experimental results were substantiated by a theoretical model. The present values of the magnetocaloric effect are higher than those of many undoped chromites, manganites and molecular magnets in the liquid helium temperature range.
- Published
- 2022
31. van der Waals oxide heteroepitaxy for soft transparent electronics
- Author
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Yugandhar Bitla and Ying-Hao Chu
- Subjects
Computer science ,Graphene ,Transistor ,Nanotechnology ,Substrate (printing) ,Flexible electronics ,Clamping ,law.invention ,symbols.namesake ,law ,Scalability ,symbols ,General Materials Science ,Electronics ,van der Waals force - Abstract
The quest for multifunctional, low-power and environment friendly electronics has brought research on materials to the forefront. For instance, as the emerging field of transparent flexible electronics is set to greatly impact our daily lives, more stringent requirements are being imposed on functional materials. Inherently flexible polymers and metal foil templates have yielded limited success due to their incompatible high-temperature growth and non-transparency, respectively. Although the epitaxial-transfer strategy has shown promising results, it suffers from tedious and complicated lift-off-transfer processes. The advent of graphene, in particular, and 2D layered materials, in general, with ultrathin scalability has revolutionized this field. Herein, we review the direct growth of epitaxial functional oxides on flexible transparent mica substrates via van der Waals heteroepitaxy, which mitigates misfit strain and substrate clamping for soft transparent electronics applications. Recent advances in practical applications of flexible and transparent electronic elements are discussed. Finally, several important directions, challenges and perspectives for commercialization are also outlined. We anticipate that this promising strategy to build transparent flexible optoelectronic devices and improve their performance will open up new avenues for researchers to explore.
- Published
- 2020
32. Structural and magnetic properties of holmium and zirconium co-substituted bismuth ferrite
- Author
-
Sudarsana S. Menon, Suresh Pittala, P. S. Anil Kumar, Yugandhar Bitla, and Keerthana S. Kumar
- Subjects
Zirconium ,Materials science ,Analytical chemistry ,chemistry.chemical_element ,Coercivity ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,Ferromagnetism ,Phase (matter) ,symbols ,Crystallite ,Holmium ,Raman spectroscopy ,Bismuth ferrite - Abstract
Polycrystalline Bi1-xHoxFe1-yZryO3 series has been synthesized by sol-gel method. The effect of Ho, Zr co- substitution on structure and magnetic properties were investigated. The results of the XRD patterns suggest that all the samples have a rhombohedral structure (space group R3c). The lattice parameters increase as the Ho, Zr concentration increases. Raman spectroscopy show vibration modes for all the samples associated with R3c phase accompanying a shift in the modes due to co-substitution of Ho and Zr. As Ho, Zr doping level increases, the weak ferromagnetism becomes more obvious with the effect that the saturation magnetization and coercivity gradually increases and attain maxima at x = y = 0.2.
- Published
- 2020
33. Deterministic, Reversible, and Nonvolatile Low-Voltage Writing of Magnetic Domains in Epitaxial BaTiO3/Fe3O4 Heterostructure
- Author
-
Xiangli Zhong, Feng An, Yugandhar Bitla, Shuhong Xie, Jiangyu Li, Junxi Yu, Yun Ou, Wenpei Gao, Yi Zhang, Jinbin Wang, Xiaoqing Pan, Gaokuo Zhong, Ying-Hao Chu, Congbing Tan, Jie Jiang, and Ying-Hui Hsieh
- Subjects
Materials science ,Spintronics ,Magnetic moment ,Magnetic domain ,business.industry ,General Engineering ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Ferroelectricity ,0104 chemical sciences ,Magnetic field ,Condensed Matter::Materials Science ,Magnetization ,Electric field ,Optoelectronics ,General Materials Science ,Magnetic force microscope ,0210 nano-technology ,business - Abstract
The ability to electrically write magnetic bits is highly desirable for future magnetic memories and spintronic devices, though fully deterministic, reversible, and nonvolatile switching of magnetic moments by electric field remains elusive despite extensive research. In this work, we develop a concept to electrically switch magnetization via polarization modulated oxygen vacancies, and we demonstrate the idea in a multiferroic epitaxial heterostructure of BaTiO3/Fe3O4 fabricated by pulsed laser deposition. The piezoelectricity and ferroelectricity of BaTiO3 have been confirmed by macro- and microscale measurements, for which Fe3O4 serves as the top electrode for switching the polarization. X-ray absorption spectroscopy and X-ray magnetic circular dichroism spectra indicate a mixture of Fe2+ and Fe3+ at O h sites and Fe3+ at T d sites in Fe3O4, while the room-temperature magnetic domains of Fe3O4 are revealed by microscopic magnetic force microscopy measurements. It is demonstrated that the magnetic domains of Fe3O4 can be switched by not only magnetic fields but also electric fields in a deterministic, reversible, and nonvolatile manner, wherein polarization reversal by electric field modulates the oxygen vacancy distribution in Fe3O4, and thus its magnetic state, making it attractive for electrically written magnetic memories.
- Published
- 2018
34. Tuning Fe concentration in epitaxial gallium ferrite thin films for room temperature multiferroic properties
- Author
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Xiangjian Meng, Jiangyu Li, Yi Zhang, Xiangli Zhong, Ehsan Nasr Esfahani, Yi Ying Chin, Yuan Zhang, Ahmad Eshghinejad, Wenpei Gao, Gaokuo Zhong, Jinbin Wang, Qingfeng Zhu, Hong-Ji Lin, Feng An, Yugandhar Bitla, Shuhong Xie, Congbing Tan, Xiaoqing Pan, and Ying-Hao Chu
- Subjects
Materials science ,Polymers and Plastics ,Magnetic moment ,Condensed matter physics ,Magnetism ,Metals and Alloys ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Ferroelectricity ,Electronic, Optical and Magnetic Materials ,Pyroelectricity ,Pulsed laser deposition ,Piezoresponse force microscopy ,0103 physical sciences ,Ceramics and Composites ,Multiferroics ,Thin film ,010306 general physics ,0210 nano-technology - Abstract
Stoichiometric gallium ferrite (GFO) is a promising single-phase multiferroic material at room temperature. Nevertheless, simultaneous magnetism and ferroelectricity in a single GFO at room temperature has not been demonstrated yet. In this work, single-phase GFO thin films with different amount of excessive Fe have been successfully grown using a dual target pulsed laser deposition (PLD) process, and the magnetic transition temperature is found to be above room temperature with excessive Fe distributed among the available cation sites of GFO unit cell. Ferroelectricity of GFO films have been confirmed by second harmonic generation (SHG), polarization hysteresis, pyroelectric reversal, and piezoresponse force microscopy (PFM), and magnetoelectric (ME) coupling has been demonstrated by increase in piezoresponse induced via external magnetic field applied in-plane, all measured at room temperature. From the data, it is theorized that the magnetic properties of GFO originate from the superexchange interaction mediated via the Fe1-O-Fe2 bond, and an additional Fe1-O-Fe* bond can form from excess Fe atoms. Under a magnetic field applied along c axis, the magnetic moment of Fe2 and Fe* increase while that of Fe1 decreases, and these changes in magnetic moment result in larger distortion of Fe2 and Fe* octahedrons along the b-axis, and thus enhanced polarization and piezoresponse. This series of studies thus confirm single-phase GFO with excessive Fe as a multiferroic material at room temperature with ME coupling, paving way for its potential functional applications in microelectronic and spintronic devices.
- Published
- 2018
35. Self-assembling epitaxial growth of a single crystalline CoFe2O4 nanopillar array via dual-target pulsed laser deposition
- Author
-
Xiaoqing Pan, Jiangyu Li, Xiangli Zhong, Feng An, Jinbin Wang, Shuhong Xie, Yugandhar Bitla, Gaokuo Zhong, Yi Zhang, Mao Ye, and Wenpei Gao
- Subjects
Fabrication ,Materials science ,business.industry ,Magnetism ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Epitaxy ,01 natural sciences ,0104 chemical sciences ,Pulsed laser deposition ,X-ray photoelectron spectroscopy ,Scanning transmission electron microscopy ,Materials Chemistry ,Optoelectronics ,Magnetic force microscope ,0210 nano-technology ,business ,Nanopillar - Abstract
Magnetic nanopillars are promising for a variety of technological applications, though the template-free fabrication of magnetic nanopillar arrays with good crystallinity and uniform distribution remains a substantial challenge. Herein, we report successful fabrication of a regular array of CoFe2O4 (CFO) nanopillars using an elaborately designed dual-target pulsed laser deposition (PLD) process, which exhibit a truncated pyramid surface with consistent size and orientation as well as uniform distribution. Detailed X-ray diffraction, scanning transmission electron microscopy and X-ray photoelectron spectroscopy demonstrate the high quality nature of the CFO nanopillars, while vibrating sample magnetometer and magnetic force microscopy studies confirm their room temperature magnetism. This dual-target PLD process takes advantage of BiFeO3 decomposition, and the subsequent formation of CFO nanopillars requires no template, giving us a powerful technique to prepare oxide nanopillars with desired composition and functional properties.
- Published
- 2018
36. Optical manipulation of nebulizer spray pyrolysed ZnS thin films for photodetector applications: Effect of Al, Sn and Sb doping
- Author
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M. Karunakaran, V. Ganesh, I.S. Yahia, Naidu Dhanpal Jayram, S. Vinoth, Yugandhar Bitla, A. Jesu Jebathew, Hamed Algarni, and Ramesh Ade
- Subjects
Materials science ,business.industry ,Band gap ,Organic Chemistry ,Doping ,Analytical chemistry ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Inorganic Chemistry ,Responsivity ,Semiconductor ,Quantum efficiency ,Crystallite ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Thin film ,business ,Spectroscopy ,Wurtzite crystal structure - Abstract
In this work, we report the structural, morphological, optical and photo-sensing properties of pure as well as Al, Sn and Sb-doped ZnS thin films, with the prospect of photo-sensing and photo-detection applications. ZnS, ZnS:Al(1%), ZnS:Sn(1%) and ZnS:Sb(1%) thin films are fabricated by the spray pyrolysis method. These thin films exhibit polycrystalline nature and crystallize in hexagonal wurtzite ZnS structure. Optical properties reveal the semiconductor behavior of all the films. The optical bandgap (Eg) values, which are around 3.67 eV, 3.43 eV, 3.32 eV and 3.56 eV for ZnS, ZnS:Al(1%), ZnS:Sn(1%) and ZnS:Sb(1%) thin films, respectively, decrease with Al, Sn and Sb-doping. On the other hand, doping of Al, Sn and Sb into the ZnS lattice enhances the photo-sensing parameters such as responsivity (R) and external quantum efficiency (EQE). Al-doping into the ZnS does not affect detectivity (D*) but Sb-doping results in a decrement of D*-value. ZnS:Sn(1%) photo-detector exhibits the highest R, EQE and D*-values of 1.05 × 10−1 AW−1, 33.9% and 4.29 × 1010 Jones, respectively, among all the fabricated photo-devices. Thus doping of post-transition (Al, Sn) and metalloid (Sb) elements into the ZnS host lattice significantly alter the optical and photo-sensing properties of the present thin films.
- Published
- 2021
37. Unveiling the magnetic and transport properties of La0.5Sr0.5Co1−xVxO3−δ (x = 0, 0.01, 0.02 and 0.1)
- Author
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Ajit K. Patra, Ram Janay Choudhary, Rishabh Shukla, U.P. Mohammed Rasi, R. B. Gangineni, Nancy, Subasa C. Sahoo, M. Vasundhara, Yugandhar Bitla, and Bommareddy Poojitha
- Subjects
010302 applied physics ,Materials science ,Spin states ,Magnetic moment ,Photoemission spectroscopy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Ion ,Condensed Matter::Materials Science ,Delocalized electron ,Ferromagnetism ,Chemical physics ,0103 physical sciences ,Curie temperature ,Condensed Matter::Strongly Correlated Electrons ,0210 nano-technology ,Spin (physics) - Abstract
La0.5Sr0.5CoO3−δ system displaying coexistence of metallicity and ferromagnetism, and the interplay between distinct spin states of Co ions has gained significant attention from the fundamental as well as the applications point of view. In this regard, the effect of V5+ doping on the dynamics of spin and oxidation states of Co ions in the La0.5Sr0.5CoO3−δ system has been studied using structural, X-ray photoemission spectroscopy, magnetic and transport measurements. The La0.5Sr0.5Co1−xVxO3−δ (x = 0, 0.01, 0.02 and 0.1) series was prepared by conventional solid-state reaction method and its chemical homogeneity was established by inductively coupled plasma mass spectroscopy. The increase of lattice parameters/volume with increasing V5+ content in rhombohedrally crystallized (R 3 - c) samples is attributed to the presence of Co2+ ions . The presence of Co2+ ions and the reduction of Co3+ ion concentration with V substitution is verified from the results of core-level photoemission spectra of Co. Detailed magnetic measurements show an increase in Curie temperature, effective magnetic moment, soft magnetic nature and suggesting strengthening of underlying magnetic interactions. As a result of multiple oxidation states of Co ions and the delocalization of electrons, rise in the conductivity is noticed. Such enhancement in the conductivity and ferromagnetic ordering temperature, simultaneously, with V doping implies a strong coupling between spin and charge degrees of freedom. To understand the underlying mechanism more clearly, different possible scenarios have been discussed. The most appropriate scenario i.e., the conversion of Co3+ ions into Co2+ ions and admixture of Co4+ ion spin states with V5+ doping was found to be consistent with all the experimental observations.
- Published
- 2021
38. MICAtronics: A new platform for flexible X-tronics
- Author
-
Ying-Hao Chu and Yugandhar Bitla
- Subjects
Materials science ,Nanotechnology ,Heterojunction ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Epitaxy ,01 natural sciences ,Flexible electronics ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Materials Chemistry ,Ceramics and Composites ,Van der waals epitaxy ,Mica ,Electronics ,Thin film ,0210 nano-technology ,Material properties - Abstract
In the present era of “Internet-of-Things”, the demand for flexible, light-weight, low-cost, low-power consumption, multifunctional, and environmentally friendly electronics has moved to the forefront of materials science research. Numerous compounds with unique material properties in epitaxial thin film form hold key to future technologies. van der Waals epitaxy (vdWE) involving two-dimensional layered materials can play a crucial role in the expansion of thin film epitaxy by overcoming the bottleneck of material combinations due to lattice/thermal matching conditions inherent to conventional epitaxy. Among the layered materials, mica is a well-known phyllosilicate mineral that can have a remarkable impact on flexible electronics. We confine ourselves to the validity of vdWE of functional oxides on muscovite mica throughout this treatise. These heterostructures with excellent properties are flexible and exhibit high-temperature stability. With such demonstrations, it is anticipated that MICAtronics, vdWE on mica, can reveal unusual properties and emergent phenomena in the realm of high-performance flexible device applications.
- Published
- 2017
39. Enhancing the properties of CdO thin films by co-doping with Mn and Fe for photodetector applications
- Author
-
B. Ravi Kumar, K. Kasirajan, Yugandhar Bitla, S. AlFaify, M. Karunakaran, V. Ganesh, I.S. Yahia, and K. Hari Prasad
- Subjects
010302 applied physics ,Electron mobility ,Materials science ,Photoluminescence ,Absorption spectroscopy ,Doping ,Metals and Alloys ,Analytical chemistry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Field electron emission ,Electrical resistivity and conductivity ,0103 physical sciences ,Direct and indirect band gaps ,Electrical and Electronic Engineering ,Thin film ,0210 nano-technology ,Instrumentation - Abstract
In this communication, we report on how the co-doping of two transition metal ions (Fe and Mn) effectively improves the structural, morphological, optical, electrical and photodetection properties of CdO thin films than individual doping. For this, pure-CdO, Fe-doped, Mn-doped and (Fe-Mn) co-doped CdO thin films are deposited by spray pyrolysis technique. X-ray diffraction (XRD) patterns reveal that these films possess cubic structure and belong to the Fm-3 m space group. The Field Emission Scanning Electron micrographs hold a qualitative agreement with the crystalline sizes obtained from the XRD analysis. Energy Dispersive X-Ray Analysis approved the existence of constituent elements in the prepared films. The photoluminescence spectra identified the quality of crystal structure and the presence of defects in the prepared films. Analyzing the absorption spectra unveiled the direct bandgap values in the range 2.32 eV (for pure-CdO) - 1.96 eV (for CdO:Fe(1%):Mn(1%)). The Hall Effect measurements established n-type behavior with the values of resistivity (ρ), carrier concentration (n) and carrier mobility values in the range 5.8–7.1 mΩcm, 6.7−2.4 × 1019 cm−3 and 16−37 cm2/Vs, respectively. Three different transport mechanisms such as ohmic, recombination-tunneling and space-charge limited current are found to play roles in the three distinct ranges of the I–V data measured for the films under study. The ideality factor values are obtained from the region where the recombination-tunneling mechanism is prevalent. The photoelectric parameters such as photo-responsivity, and external quantum efficiency are obtained. The values of these quantities pertaining to pure-CdO, CdO:Mn, CdO:Fe and CdO:Fe:Mn films vary in the range 128.4–561.3 mA/W, and 30–131.1 %, respectively. From the current study, it was found that photoresponsivity and external quantum efficiency are enhanced by a factor of four in codoped CdO films than the undoped CdO film and can find potential photodetector applications.
- Published
- 2021
40. Effect of Ti doping on structural, optical and electrical properties of SnO2 transparent conducting thin films deposited by sol-gel spin coating
- Author
-
V. Ganesh, T. Ranjeth Kumar Reddy, G. Srinivas Reddy, Peddavarapu Sivakumar, Harish Sharma Akkera, Madhukar Poloju, P. Mohan Kumar, and Yugandhar Bitla
- Subjects
Spin coating ,Materials science ,Band gap ,Organic Chemistry ,Doping ,Analytical chemistry ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Inorganic Chemistry ,Rutile ,Electrical resistivity and conductivity ,Crystallite ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Thin film ,0210 nano-technology ,Spectroscopy ,Sheet resistance - Abstract
In the present work, various concentrations of Ti (1, 2, 3, 4 and 5 at %) doped SnO2 thin films were grown onto glass substrate using cost effective sol-gel spin coating method and subsequently investigated the effect of Ti doping concentration on structural, optical and electrical properties. X-ray diffraction studies revealed that all deposited films exhibit polycrystalline tetragonal rutile structure with fundamental orientation peak along (110) direction. Moreover, Ti doped SnO2 films were started growing along (211) direction and it was more pronounced with increasing of Ti concentration. The average grain size was decreased with the increase of Ti concentration, confirmed by XRD and AFM studies. The UV–visible spectrometer measurements shown that the average transmittance of un-doped SnO2 film was above 85%, whereas Ti doped SnO2 films were found to be a decrease of transmittance up to 77% in 5 at% Ti:SnO2 film. The optical band gap energy values were considerably decreased from 3.91 to 3.73 eV with increase of Ti content. Further, the sheet resistance (Rsh) and resistivity (ρ) values were found to be decreased with the increase of Ti doping up to 3 at % then it was slightly increased in 4 and 5 at % of Ti:SnO2 films. The efficiency parameter figure of merit (φ) was also estimated for all deposited films with the function of Ti doping.
- Published
- 2021
41. Enhanced Structural and Magnetic Coupling in a Mesocrystal-Assisted Nanocomposite
- Author
-
Ying-Hao Chu, Qian Zhan, Elke Arenholz, V. Suresh Kumar, Chen I. Li, Yuanmin Zhu, Heng Jui Liu, Pingping Liu, Jan Chi Yang, Yugandhar Bitla, and Qing He
- Subjects
010302 applied physics ,Structural phase ,Materials science ,Nanocomposite ,Nanotechnology ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Structural evolution ,Inductive coupling ,Octahedron ,Nanocrystal ,0103 physical sciences ,General Materials Science ,0210 nano-technology ,Mesocrystal ,Absorption (electromagnetic radiation) - Abstract
Benefiting from the advances made in well-controlled materials synthesis techniques, nanocomposites have drawn considerable attention due to their enthralling physics and functionalities. In this work, we report a new heteroepitaxial mesocrystal-perovskite nanocomposite, (NiFe2O4)0.33:(La0.67Ca0.33MnO3)0.67. Elaborate structural studies revealed that tiny NiFe2O4 nanocrystals aggregate into ordered octahedral mesocrystal arrays with {111} facets together with a concomitant structural phase transition of the La0.67Ca0.33MnO3 matrix upon postannealing process. Combined magnetic and X-ray absorption spectroscopic measurements show significant enhancement in the magnetic properties at room temperature due to the structural evolution of magnetic NiFe2O4 and the consequent magnetic coupling at the heterointerfaces mediating via well connected octahedrons of Mn-O6 in La0.67Ca0.33MnO3 and (Ni,Fe)-O6 in NiFe2O4. This work demonstrates an approach to manipulate the exciting physical properties of material systems by integrating desired functionalities of the constituents via synthesis of a self-assembled mesocrystal embedded nanocomposite system.
- Published
- 2016
42. Magnetotransport in under and optimally hole-doped bulk nanocrystalline La1-xCaxMnO3 manganites
- Author
-
S. N. Kaul, P.D. Babu, and Yugandhar Bitla
- Subjects
Phase transition ,Colossal magnetoresistance ,Materials science ,Ferromagnetism ,Condensed matter physics ,Electrical resistivity and conductivity ,Condensed Matter Physics ,Manganite ,Variable-range hopping ,Temperature coefficient ,Electron localization function ,Electronic, Optical and Magnetic Materials - Abstract
Electrical-transport and magneto-transport in bulk nanocrystalline (BNC) La 1 - x Ca x MnO 3 + δ (x = 1/8 with either δ = 0.00 or δ = 0.06, x = 3/8 with δ = 0.00) (LCMO) manganite system have been studied treating the bulk crystalline (BC) counterparts as the reference systems. Irrespective of the value of δ in under hole-doped (x = 1/8) LCMO, the metal-insulator (M-I) transition (not observed in the BC counterpart) appears at a temperature T MI ≪ T C , where T C is the temperature at which the ferromagnetic (FM)–paramagnetic (PM) second-order phase transition occurs. Oxygen off-stoichiometry makes the M-I transition more pronounced and reduces the overall magnitude of resistivity. Reducing the average crystallite size d below 150 nm, lowers both T MI and T C in the BNC samples with x = 1/8 and δ = 0.00 or 0.06 but decreases T MI while increasing T C in the optimally hole-doped x = 3/8 LCMO. The single-orbital double-exchange model, which predicts the coincidence, or otherwise, of the M-I and FM-PM transitions with some success in the BC LCMO, fails to correctly describe the above-mentioned results in BNC LCMO. The resistivity minima at low temperatures ( T min ), completely absent in BC, occur in BNC LCMO, regardless of the value of x , δ , d and the strength of the magnetic field (H). The mechanism for resistivity, ρ (T), changes from the adiabatic small polaron nearest-neighbor hopping (for x = 3/8) or from the Shklovskii-Efros variable range hopping, SE-VRH, (for x = 1/8), prevalent in BC, to the Mott-VRH in the PM insulating state in the BNC counterparts when d falls below 150 nm. At T T min , the contributions due to the Mott-VRH (present only in the samples with x = 1/8 and δ = 0.00 or δ = 0.06) and the enhanced electron-electron Coulomb interaction (in all the BNC LCMO samples) are responsible for the negative temperature coefficient of resistivity (TCR). By contrast, the coherent electron-magnon scattering accounts for the positive TCR observed at T > T min . H suppresses the mean hopping energy difference between the hopping sites but increases the electron localization length. The field-induced enhancement in the localization length far outweighs the field-induced drop in the mean hopping energy difference to produce an increase in the mean hopping distance with H.
- Published
- 2020
43. A facile synthesis of Au-nanoparticles decorated PbI2 single crystalline nanosheets for optoelectronic device applications
- Author
-
Ajeet Kaushik, Mohd. Shkir, S. AlFaify, Yugandhar Bitla, I.M. Ashraf, V. Ganesh, and I.S. Yahia
- Subjects
Multidisciplinary ,Materials science ,Photoluminescence ,business.industry ,Band gap ,Photoconductivity ,lcsh:R ,lcsh:Medicine ,Photodetector ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Article ,0104 chemical sciences ,Absorption band ,Optoelectronics ,lcsh:Q ,lcsh:Science ,0210 nano-technology ,business ,Excitation ,Localized surface plasmon - Abstract
This research communication presents a rapid and facile microwave-assisted synthesis of single crystalline nanosheets (SCNSs) of hexagonal lead iodide (PbI2) decorated with Au nanoparticles, a potential optoelectronics material. Homogeneous low dimensional AuNP decoration in PbI2 resulted in a new absorption band at ~604 nm and a shift in band gap from 3.23 to 3.00 eV. The significant enhancement of photoluminescent (PL) intensity observed in the AuNP-PbI2 SCNSs is attributed to the coupling of the localized surface plasmon resonanzce of AuNP leading to improved excitation and emission rates of PbI2-SCNSs in the region of the localized electromagnetic field. The Au-PbI2 SCNSs display a compelling increment in photoconductivity, and its fabricated photodetector showed a stable and switchable photo-response. Due to ease of synthesis and enhanced photoconductivity along with appealing PL features, Au-PbI2 SCNS has the potential to be used as a material of choice when fabricating an optoelectronic devices of high performance.
- Published
- 2018
44. Emergence of electron-phonon coupling in a dual topological insulator BiTe
- Author
-
P. S. Anil Kumar, Shoubhik Mandal, R. Ganesan, Yugandhar Bitla, and Debarghya Mallick
- Subjects
Biomaterials ,Physics ,Polymers and Plastics ,Condensed matter physics ,Topological insulator ,Metals and Alloys ,Electron phonon coupling ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Dual (category theory) - Published
- 2019
45. Deterministic, Reversible, and Nonvolatile Low-Voltage Writing of Magnetic Domains in Epitaxial BaTiO
- Author
-
Gaokuo, Zhong, Feng, An, Yugandhar, Bitla, Jinbin, Wang, Xiangli, Zhong, Junxi, Yu, Wenpei, Gao, Yi, Zhang, Congbing, Tan, Yun, Ou, Jie, Jiang, Ying-Hui, Hsieh, Xiaoqing, Pan, Shuhong, Xie, Ying-Hao, Chu, and Jiangyu, Li
- Abstract
The ability to electrically write magnetic bits is highly desirable for future magnetic memories and spintronic devices, though fully deterministic, reversible, and nonvolatile switching of magnetic moments by electric field remains elusive despite extensive research. In this work, we develop a concept to electrically switch magnetization via polarization modulated oxygen vacancies, and we demonstrate the idea in a multiferroic epitaxial heterostructure of BaTiO
- Published
- 2018
46. Enhancing the Magnetic Moment of Ferrimagnetic NiCo2O4 via Ion Irradiation driven Oxygen Vacancies
- Author
-
Parul Pandey, Yugandhar Bitla, Matthias Zschornak, Mao Wang, Chi Xu, Jörg Grenzer, Dirk-Carl Meyer, Yi-Ying Chin, Hong-Ji Lin, Chien-Te Chen, Sibylle Gemming, Manfred Helm, Ying-Hao Chu, and Shengqiang Zhou
- Subjects
Condensed Matter::Materials Science ,lcsh:Biotechnology ,lcsh:TP248.13-248.65 ,lcsh:Physics ,lcsh:QC1-999 - Abstract
Ion irradiation has emerged as a powerful tool for the efficient control of uniaxial lattice expansion to fine tune and modulate the otherwise inaccessible complex correlated phases in oxide thin-films. We report the fine tuning of the magnetic moment, ferromagnetic-paramagnetic and metal-insulator transition temperatures in the NiCo2O4 inverse-spinel oxide by creating oxygen deficiencies, employing high energy He-ion irradiation. Tailoring of oxygen vacancies and consequently a uniaxial lattice expansion in the out-of-plane direction drives the system toward the increase of the magnetic moment by two-times in magnitude. The magnetic moment increases with the He-ion irradiation fluence up to 2.5 × 1016/cm2. Our results are corroborated well by spin-polarized electronic structure calculations with density functional theory and X-ray absorption spectroscopic data, which show peak-height change and energy shift of Co-L2,3 and Ni-L2,3 edges driven by the oxygen vacancies. These results demonstrate a new pathway of tailoring oxygen vacancies via He-ion irradiation, useful for designing new functionalities in other complex oxide thin-films.
- Published
- 2018
47. Flexible Multiferroic Bulk Heterojunction with Giant Magnetoelectric Coupling via van der Waals Epitaxy
- Author
-
Kee Hoon Kim, Yugandhar Bitla, Jenh-Yih Juang, Shien-Uang Jen, Heng Jui Liu, Yi-Chun Chen, Tahta Amrillah, Yu You Chiou, Ying Hui Hsieh, Long Qing Chen, Tiannan Yang, Kwangwoo Shin, Thi Hien Do, Dong Su, and Ying-Hao Chu
- Subjects
Materials science ,Nanocomposite ,Spintronics ,business.industry ,General Engineering ,General Physics and Astronomy ,Heterojunction ,Nanotechnology ,02 engineering and technology ,Substrate (electronics) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Epitaxy ,01 natural sciences ,Polymer solar cell ,0104 chemical sciences ,Optoelectronics ,General Materials Science ,Multiferroics ,0210 nano-technology ,business ,Nanopillar - Abstract
Magnetoelectric nanocomposites have been a topic of intense research due to their profound potential in the applications of electronic devices based on spintronic technology. Nevertheless, in spite of significant progress made in the growth of high-quality nanocomposite thin films, the substrate clamping effect still remains a major hurdle in realizing the ultimate magnetoelectric coupling. To overcome this obstacle, an alternative strategy of fabricating a self-assembled ferroelectric–ferrimagnetic bulk heterojunction on a flexible muscovite via van der Waals epitaxy is adopted. In this study, we investigated the magnetoelectric coupling in a self-assembled BiFeO3 (BFO)–CoFe2O4 (CFO) bulk heterojunction epitaxially grown on a flexible muscovite substrate. The obtained heterojunction is composed of vertically aligned multiferroic BFO nanopillars embedded in a ferrimagnetic CFO matrix. Moreover, due to the weak interaction between the flexible substrate and bulk heterojunction, the interface is incoherent ...
- Published
- 2017
48. Flexible ferroelectric element based on van der Waals heteroepitaxy
- Author
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Yichun Zhou, Yu Hong Lai, Yi-Chun Chen, Chun Wei Huang, Po-Wen Chiu, Thi Hien Do, Chun Hao Ma, Yugandhar Bitla, Jie Jiang, Ying Hui Hsieh, Ying-Hao Chu, Wen-Wei Wu, Chi Yuan Jang, and Heng Jui Liu
- Subjects
Fabrication ,Materials science ,flexible memory ,PZT ,Materials Science ,Nanotechnology ,02 engineering and technology ,Bending ,Hardware_PERFORMANCEANDRELIABILITY ,010402 general chemistry ,Epitaxy ,01 natural sciences ,symbols.namesake ,Reliability (semiconductor) ,epitaxial thin films ,Hardware_GENERAL ,ferroelectric materials ,Hardware_INTEGRATEDCIRCUITS ,Electronics ,Research Articles ,Multidisciplinary ,Hardware_MEMORYSTRUCTURES ,business.industry ,SciAdv r-articles ,021001 nanoscience & nanotechnology ,Ferroelectricity ,0104 chemical sciences ,Non-volatile memory ,van der Waals heteroepitaxy ,symbols ,Optoelectronics ,van der Waals force ,0210 nano-technology ,business ,Research Article - Abstract
A flexible ferroelectric memory element based on oxide heteroepitaxy has been demonstrated with superior performance., We present a promising technology for nonvolatile flexible electronic devices: A direct fabrication of epitaxial lead zirconium titanate (PZT) on flexible mica substrate via van der Waals epitaxy. These single-crystalline flexible ferroelectric PZT films not only retain their performance, reliability, and thermal stability comparable to those on rigid counterparts in tests of nonvolatile memory elements but also exhibit remarkable mechanical properties with robust operation in bent states (bending radii down to 2.5 mm) and cycling tests (1000 times). This study marks the technological advancement toward realizing much-awaited flexible yet single-crystalline nonvolatile electronic devices for the design and development of flexible, lightweight, and next-generation smart devices with potential applications in electronics, robotics, automotive, health care, industrial, and military systems.
- Published
- 2017
49. Oxide Heteroepitaxy for Flexible Optoelectronics
- Author
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Li Chang, Thi Hien Do, Hsien Chang Lee, Po-Wen Chiu, Ching Chen, Chun Hao Ma, Le Van Qui, Chun Wei Huang, Wen-Wei Wu, Ying-Hao Chu, and Yugandhar Bitla
- Subjects
Fabrication ,Materials science ,Silicon ,Oxide ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Epitaxy ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Fabrication methods ,General Materials Science ,Mica substrate ,Electronics ,0210 nano-technology ,Alternative strategy - Abstract
The emerging technological demands for flexible and transparent electronic devices have compelled researchers to look beyond the current silicon-based electronics. However, fabrication of devices on conventional flexible substrates with superior performance are constrained by the trade-off between processing temperature and device performance. Here, we propose an alternative strategy to circumvent this issue via the heteroepitaxial growth of transparent conducting oxides (TCO) on the flexible mica substrate with performance comparable to that of their rigid counterparts. With the examples of ITO and AZO as a case study, a strong emphasis is laid upon the growth of flexible yet epitaxial TCO relying muscovite's superior properties compared to those of conventional flexible substrates and its compatibility with the present fabrication methods. Besides excellent optoelectro-mechanical properties, an additional functionality of high-temperature stability, normally lacking in the current state-of-the-art transparent flexitronics, is provided by these heterostructures. These epitaxial TCO electrodes with good chemical and thermal stabilities as well as mechanical durability can significantly contribute to the field of flexible, light-weight, and portable smart electronics.
- Published
- 2016
50. Growth of Flexible NiFe2O4 Thin Films Via Van Der Waal Heteroepitaxy
- Author
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Yugandhar Bitla and Ying-Hao Chu
- Subjects
Materials science ,Spintronics ,business.industry ,Ferrimagnetism ,Optoelectronics ,Curie temperature ,Magnetostriction ,Thin film ,business ,Ferroelectricity ,Microwave ,Pulsed laser deposition - Abstract
The growth of high quality single crystalline NiFe 2 O 4 (NFO) thin films has been seriously pursued recently as a prime candidate for sensors, spin filter devices, circuit elements, memory, and magnetoelectric composites 1–2. This is due to the fact that inverse spinel NFO has high Curie temperature, high saturation magnetization, moderate magnetostriction, large exchange splitting and a wide band-gap. In this work, we demonstrate the epitaxial growth of NFO(111) thin films on flexible and transparent muscovite mica substrate via Van der Waal heteroepitaxy using pulsed laser deposition technique. Detailed structural and magnetic characterizations revealed that NFO thin films retain the inverse spinel structure and exhibit room temperature ferrimagnetism. The NFO was further integrated with a ferroelectric material for the realization of magnetoelectric phenomenon at microwave frequencies necessary for the electric field tunable microwave phase shifters and band-pass filters. Therefore, our approach not only offers great opportunities for next generation reconfigurable RF/microwave communication systems, Spintronics, magnetic field sensors, etc. but also provide a framework for realizing compact, light-weight, and ultralow power electronics and microwave devices.
- Published
- 2016
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