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In the era of Photonics, design and development of novel rare earth ion-doped quantum dots (QDs) for optoelectronic applications has gained significant interest owing to their outstanding characteristics. Simultaneously, the creation of a new class of photocatalytic materials on the nanoscale is also imperative for environmental purification. Thus, we report on wet chemical synthesis, the structural, morphological, and optical characteristics, fluorescence, and hydrogen evolution of ZnS:Eu (0, 2, 4, and 6 at%) QDs for optoelectronic and photocatalytic applications. Comprehensive structural studies depicted that Eu3+ ions were efficiently substituted into the host matrix and altered the original structure of the ZnS compound. The emission spectra of the ZnS:Eu QDs exhibited distinctive red fluorescence owing to the transition of dopant ions in 5D0 - 7F1, 5D0 - 7F2, 5D0 - 7F3, and 5D0 - 7F4 energy levels of the 4f orbital of the Eu3+ ions. Moreover, the photocatalytic properties of ZnS:Eu (6 at%) QDs possess better catalytic efficiency toward hydrogen evolution through a water splitting mechanism under simulated sunlight irradiation. The observed photocatalytic phenomenon in the synthesized samples agreed well with the luminescence properties exhibited by the QDs.

In the present study, we fabricate the ZnS: V (0, 2, 4, and 6 at%) nanoparticles (NPs) using the chemical-refluxing technique. We analyzed these samples based on structural, optical, magnetic, degradation, and hydrogen evolution properties. Comprehensive analyses of the chemical, structural, and optical measurements show that the vanadium (V) ions occupied the Zn host site without altering their original structure and without forming new phases. We confirmed the paramagnetic nature of the doped samples via magnetic measurements. We examined the photocatalytic properties of the fabricated NPs by the degrading Rhodamine-B (RhB) dye in an aqueous solution under the ultraviolet (UV) light, and the ZnS: V of 2 at% displayed higher degradation efficiency than the other samples. Moreover, 2 at% ZnS: V (sample showed a higher H2 evolution rate (1140 μmolg−1h−1) than the other samples and was 17 times greater than that of pure ZnS lattice. The observed efficient photocatalytic organic pollutant degradation and better hydrogen fuel evolution in 2 at% ZnS: V sample could be due to the presence of a large surface area, creation of more defect sites, dislocation sites of the prepared compound, generation, and the presence of a huge number of charge carriers due to the substitution of V-dopant in the Zn host site and non-recombination rate of charges.

The design and production of co-doped diluted magnetic semiconductor nanostructures for the development of spin-related operating electronic devices have gained considerable attention owing to their formidable characteristics. In this study, we strived to fabricate ZnO, Zn0.98Ni0.02O, Zn0.97Ni0.02Er0.01O, and Zn0.96Ni0.02Er0.02O nanoparticles. The successful penetration of Ni and Er ions into the ZnO host material was confirmed through wide-ranging structural analyses. A slight change in the bandgap of ZnO was obtained by doping and co-doping. The photoluminescence spectra revealed that doping and co-doping induced various emissions as well as structural defects in the fabricated nanoparticles. Magnetic hysteresis loops revealed that the ZnO and Zn0.98Ni0.02O nanoparticles possessed a paramagnetic nature. However, the Zn0.97Ni0.02Er0.01O and Zn0.96Ni0.02Er0.02O nanoparticles exhibited robust ferromagnetism with clear hysteresis loops. Bound magnetic polaron behavior is well-anticipated to describe the ferromagnetism in the synthesized nanoparticles. Hence, (Ni + Er) co-doping is a promising approach for extending the ferromagnetic nature of the ZnO system for spin-based electronic devices.

Diluted magnetic semiconductors related to II–VI-based compounds are of significant interest for the development of spin-based operating electronic devices such as magneto-optical instruments, spintronics, and nonvolatile memory devices. Thus, studies of electron paramagnetic resonance, magnetic characteristics, and the photocatalytic properties of transition metal-doped II–VI-based semiconductors are of great importance. We therefore comprehensively studied the structural, electron spin resonance, magnetic hysteresis, and photocatalytic characteristics of CdS:V4+ nanoparticles (NPs) fabricated by the rapid microwave route for the first time. The structural analyses revealed the authentic substitution of V4+ dopant ions into the CdS matrix. The widening of the optical band gap and relevant quantum confinement phenomenon are discussed in terms of the inclusion of V4+ ions into the CdS matrix. The electron paramagnetic resonance (EPR) spectroscopy results were corroborated by the increase in the number of magnetic spins with increasing V4+ dopant concentration. The assessed number of magnetic spins was nearly equal to 3.601597 × 106 and 7.254048 × 106 for the CdS:V (2 and 4 at%) NPs, respectively. Room-temperature magnetic hysteresis loops also revealed the existence of a large number of magnetic spins through the formation of clear paramagnetism in the CdS:V (2 and 4 at%) NPs. The CdS:V (4 at%) system displayed enriched visible light-driven photocatalytic degradation efficiency compared to bare CdS through the degradation of RhB dye in contaminated water.

Generation of hydrogen fuel via the photocatalytic water splitting mechanism using semiconductor nanoparticles under sunlight irradiation is highly important. Moreover, the development of nanophotocatalysts for polluted water treatment is significant. In this regard, we synthesized CdS, CdS:Er (2 at%), and CdS:Er (4 at%) nanoparticles by a simple reflux route. According to the comprehensive structural analysis, Er3+ ions were incorporated into the CdS host lattice at the substitutional and interstitial sites, without altering the original structure. Photocatalytic measurements revealed that the degradation efficiency of 2 at% Er-doped CdS nanoparticles reached 100% within 100 min of visible light irradiation. In addition, CdS:Er (2 at%) nanoparticles exhibited enhanced photocatalytic hydrogen generation ability under simulated sunlight irradiation. Hence, from the obtained results, we concluded that CdS:Er (2 at%) nanoparticles are promising semiconductor photocatalytic materials for wastewater treatment as well as hydrogen fuel generation.

This study examined the characteristics of localized surface plasmon resonance (LSPR)-enhanced GaN-based light-emitting diodes (LEDs) fabricated using colloidal silver nanoparticles (cAg NPs). cAg NPs were deposited on a p-GaN surface using a low-cost metal-assisted chemical etching (MAC-etch) method. MAC-etching can increase the light extraction efficiency (LEE) by producing a roughened p-GaN surface and LSPR produces high internal quantum efficiency (IQE) through an interaction of cAg NPs with the emitted light. Field-emission scanning electron microscopy and atomic force microscopy of the surface revealed an etched p-GaN surface with cAg NPs and a roughness of ∼ 40-45 nm. In the MAC-etch samples, XRD showed that the cAg NPs had (111) and (200) preferred orientations. In addition, the calculated grain size of the 60 min cAg NPs was 50% of the grain size of the 30 min sample. The optical characteristics of the samples were measured by photoluminescence (PL) spectroscopy, ultraviolet/visible (UV/Vis) spectroscopy, and electroluminescence (EL) spectroscopy. The MAC-etch samples showed a higher PL intensity than the normal-LEDs. The UV/Vis absorbance spectra showed that the cAg NPs on the p-GaN surface generated LSPR. The EL intensity of the MAC-etch sample for 30 min increased by approximately 25%. The results of this investigation herald the development of MAC-etching for the low-cost GaN-based LED applications that are commercially viable large-scale.

We report the fabrication of CdS:Nd nanoparticles (NPs) via an economical co-precipitation method, giving adjustable optical, magnetic and photocatalytic behavior of the nanocrystalline CdS by varying the Nd ion doping concentration. The sensible doping of Nd ions into the CdS matrix was confirmed by various structural characterization techniques. Transmission electron microscopy images demonstrated the basic spheroid shape of the nanoparticles, with sizes in the range of 8–10 nm. A doping concentration-dependent redshift was observed in the CdS NP spectra, resulting from the decrease in the bandgap. The M-H curves illustrate that the undoped sample is diamagnetic, the 2 at% Nd sample is ferromagnetic, and the 4 at% Nd sample is superparamagnetic at room temperature. Photocatalytic measurements revealed that the CdS:Nd (4 at%) sample displayed better photocatalytic activity than undoped CdS NPs. As per literature, this could be the first report on the CdS:Nd system and we believed that it will be more beneficial for the further research on the CdS:Nd system.

Magnetically polarized semiconductors are of significant interest in view of their application in spintronic devices. In this study, the microstructure and room temperature ferromagnetic characteristics of ZnO, Zn0.48Tb0.02O50, and Zn0.47Tb0.02Cu0.01O50 nanoparticles (NPs) have been reported. The crystal structure and grain size of the samples were elucidated from comprehensive structural analyses; the results revealed a wurtzite crystal structure with dopant and co-dopant ions located at substitutional or interstitial sites in the ZnO host lattice. The nanoparticles sizes estimated from X-ray diffraction were confirmed by transmission electron microscopy. Diffuse reflectance spectra and the corresponding Kubelka-Munk plots suggested band gap quenching due to the inclusion of dopant ions. Magnetic measurements revealed diamagnetic character for the bare host material, while Zn0.48Tb0.02O50 and Zn0.47Tb0.02Cu0.01O50 showed bending of hysteresis loops in the low magnetic field region and linear behavior within a certain range at higher fields, indicating ferromagnetic and paramagnetic behavior in the two regimes.

Temperature-based organic–inorganic photodiodes have recently become attractive applications in branches of science and technology with eco-friendly and hybrid concepts. Here, we describe the use of salmon DNA (SDNA) biomolecules as temperature and light sensors. We demonstrate the temperature- and light-sensitive mechanism of polarity switching in metal/organic/n-GaN bio-hybrid photodiodes based on salmon DNA-cetyltrimethylammonium chloride (SDNA-surfactant). The SDNA-surfactant/n-GaN bio-hybrid temperature photodiode (Bio-HTPD) shows negative bias shift of current (I)–voltage (V) plots by 0.70 and 0.42 V compared to zero-bias at temperatures of 275 and 300 K, respectively, under light illumination. However, the I–V plots of the Bio-HTPD moved towards positive bias by 0.08 V compared to zero-bias at 325 K under light irradiation. This phenomenon resulted in electrically negative photocurrents up to room temperature, which remarkably switched to positive photocurrents at above room temperature. The temperature variations are closely associated with charge activation and unidirectional transport in the SDNA-surfactant biomolecule. Moreover, the change from negative to positive photocurrent could be related to high electron–hole pair generation at higher transition temperature. The formation of an energy band model with thermal hopping is proposed, which explains the reasonable charge transport mechanism.

Zinc Sulfide (ZnS) quantum dots (QDs) with enhanced fluorescence efficiency and photocatalytic activity have been attained through Ga doping for the first time. Ga-doped ZnS QDs were synthesized via a solvothermal method using Polyethylene glycol (PEG) as a stabilizer. Transmission electron microscopy studies disclosed that the obtained QDs were slightly polydispersed with an average size of 5.5–3.8 nm. The results of X-ray diffraction and Raman and X-ray photoelectron spectroscopy stipulated that the Ga ions were successfully incorporated into the ZnS crystal lattice without amending their internal structure. A blue shift was noticed in the ZnS QDs when doped with Ga. The photoluminescence spectra of all the QDs displayed the same blue emission and enhanced fluorescence efficiency with increase in Ga doping content. The photocatalytic degradation of the phenol red dye under UV-light illumination was enhanced with increasing Ga doping concentration. Thus, the Ga-doped ZnS QDs are potential and favorable candidates for both photoluminescent and photocatalytic device applications.

In this study, we attempted to synthesize ZnO nanoparticles with various Eu3+ doping concentrations by a simple coprecipitation method for multifunctional applications. Morphology studies of the synthesized samples revealed the presence of hexagonal-shaped and monodispersed particles. A slight shift in the X-ray diffraction patterns of the Eu3+-doped ZnO samples confirmed the successful incorporation of the dopant ions into the host crystal. A change in the E2 (high)-mode intensity was ample evidence of intrinsic defects associated with the oxygen atoms. Diffuse reflectance spectroscopy studies provided sufficient evidence of tuning of the bandgap of ZnO by Eu3+ doping, with a typical red shift. X-ray photoelectron spectroscopy studies revealed the presence of Eu with a +3 state in the ZnO lattice. All the doped ZnO nanoparticles exhibited typical room-temperature ferromagnetism (RTFM). The Eu3+-doped samples displayed a higher photocatalytic degradation (PCD) of RhB dye under UV light illumination compared with the undoped ZnO nanoparticles. Thus, Eu3+ doping is an effective approach for enhancing the RTFM and PCD properties of ZnO for spintronic and photocatalytic applications.

A semiconductor compound, which portrays ferromagnetism with tunable optical and photoluminescence properties after a sensible doping of suitable dopant, is vital for modern spintronic and luminescent applications. In this sense, we fabricate CdS, Cd0.98Er0.02S, and Cd0.96Er0.04S nanoparticles (NPs) via an inexpensive co-precipitation way. No structural deformation was found in cubic CdS after Er (III) doping. The as-fabricated NPs demonstrated good crystallinity as well as slight changes in sizes varying 3 nm–7 nm. An X-ray photoelectron spectroscopy results confirmed that the impure-free nature of the prepared samples. A decreasing trend in the optical band gap was found by the increase in the doping level. The 1CdS NPs showed diamagnetic character, whereas the Er (III)-doped CdS NPs exhibited frail ferromagnetic character at room temperature, which slightly increased as a function of Er (III) concentration. Based on the literature, this is the initial magnetic report on the CdS:Er system and this will be very informative for the further magnetic investigations on the Er doping. Hence, the tunable optical and ferromagnetic magnetic properties of CdS:Er NPs demonstrated in this work may be beneficial for optoelectronic, solar cell and spintronic applications.

The Au/Nd2O3/n-type GaN metal/interlayer/semiconductor (MIS) junctions were fabricated with high-k rare-earth oxide interlayer and explored its electrical properties in the wide temperature range of 150–400 K. An anomalous decrease in barrier height and an increase in the ideality factor with a decrease in the temperature were observed. The anomalous barrier height and ideality factor are ascribed to a role of barrier inhomogeneities at the interface of MIS junction assuming a double Gaussian distribution of barrier heights in the temperature ranges of 150–225 K and 225–400 K. Double Gaussian distribution giving mean barrier heights of 0.84 eV and 1.23 eV and standard deviations of 0.0085 V and 0.0187 V for the two temperature regions. A modified conventional energy plot gives mean barrier height $$\left( {\overline{\Phi }_{bo} } \right)$$ and Richardson constant (A*) as 0. eV and 13.44 Acm−2 K−2 (150–225 K) and 1.23 eV and 22.85 Acm−2 K−2 (250–400 K), respectively. The estimated A* value in the temperature range of 250–400 K was closely matched with the theoretical value of n-type GaN. Moreover, results express that the obtained interface state density of the MIS junction decreases with increasing temperature. Results explained that the reverse current conduction governed by Poole–Frenkel emission at the temperature range of 150–225 K and Schottky emission at 250–400 K, respectively.

With the rapid improvement of the global economy, the role of energy has become even more vital in the 21st century. In this regard, energy storage/conversion devices have become a major, worldwide research focus. In response to this, we have prepared two-dimensional (2D)-hierarchical sheet-like ZnCo2O4 microstructures for supercapacitor applications using a simple hydrothermal method. The 2D-hierarchical sheet-like morphologies with large surface area and smaller thickness enhanced the contact area of active material with the electrolyte, which increased the utilization rate. We investigated the electrochemical performance of sheet-like ZnCo2O4 microstructures while using Cyclic voltammetry (CV), Galvanostatic charge-discharge (GCD), and Electrochemical impedance spectroscopy (EIS) analysis. The electrochemical results demonstrated that the ZnCo2O4 electrode possesses 16.13 mF cm&minus, 2 of areal capacitance at 10 &micro, A cm&minus, 2 of current density and outstanding cycling performance (170% of capacitance is retained after 1000 cycles at 500 &micro, 2). The high areal capacitance and outstanding cycling performance due to the unique sheet-like morphology of the ZnCo2O4 electrode makes it an excellent candidate for supercapacitor applications.

The scarcity of potable water can be overcome by converting the saline water in to the drinkable water. The objective of the work is to enhance the performance of solar still by using phase change material (PCM) and mixing1% concentration Nano fluid in the water. A special paraffin wax with potassium nitrate is used as PCM and graphene oxide as nanofluid. The phase change materials are used to store the heat in day time and can be used in the night time for carrying out the desalination process. The experiment results showed that the productivity of water is increased for solar still with PCM and 1%concentration of nano fluid mixed in water compared with solar still with PCM and conventional solar still. The condensed water which is collected for conventional solar still, solar still with PCM and solar still with nano fluid and PCM are1820ml, 2680mland 3430ml respectively.

Terbium (0, 2, and 4 at%)-doped ZnS quantum dots (QDs) were synthesized via a solvothermal method. The crystal structures of the synthesized QDs were determined to be zinc blend by X-ray powder diffraction (XRD) and Raman analyses. Transmission electron microscopy (TEM) studies revealed that particles with a mean size of 2–4 nm were formed. An X-ray photo electron spectroscopy (XPS) examination disclosed the existence of terbium with a trivalent state in the ZnS host lattice. The absorption bands of all QDs were located around 325 nm (3.81 eV) and were higher than that of the bulk ZnS band gap (3.67 eV), consistent with the quantum confinement effect. The photoluminescence spectra of the terbium-doped samples displayed five emission peaks at 467 nm (5D4→7F3), 491 nm (5D4 → 7F6), 460 nm (5D4 – 7F5), 484 nm (5D4 – 7F4), and 530 nm (5D4 – 7F3), respectively. The terbium-doped QDs exhibited a higher photocatalytic activity during the degradation of crystal violet dye under UV-light illumination compared to the undoped ZnS QDs. These interesting properties of terbium-doped ZnS QDs are potentially useful for both luminescent and photocatalysis applications.

An ITO-Ag islands complex as a new transparent conducting electrode (TCE) structure (on the 5 nm-thick p-InGaN/90 nm-thick p-GaN) for achieving high-performance and more reliable GaN-based LEDs were fabricated. A normal LED with a conventional ITO TCE was also compared. The surface morphological, structural, electrical and optical properties of fabricated GaN-based light-emitting diodes using a complex electrode of submicron-scaled Ag islands and ITO thin films are explored by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), current-voltage (I-V) and output power-current (L-I) techniques. Surface morphology investigations revealed Ag islands formed uniformly on the p-InGaN/p-GaN surface during rapid thermal annealing at 400 °C for 1 min in N2 ambient. The ohmic properties and overall device-performance of the suggested contact and device structures were superior to those in the conventional ITO contact and normal ITO LED structures. Based on the results of XRD and XPS measurements, the formation of the intermetallic gallide phases (AgGa) is responsible for better performance characteristics of the ITO-Ag islands device. The significant improvements are described in terms of the conducting bridge influence, highly effective micro-mirror effect, and wider photon window via the roughened structure.

In this work, we present a residue-and-polymer-free graphene transfer method by using the adhesive force between graphene and a target substrate, the hydrophobic property of graphene, and the surface tension of the solutions. We used an n-type GaN substrate as the target substrate to make a photodiode (PD). Recently, the inclusion of biomolecules in photodetection technology has attracted considerable attention in the electronics and photonics research, particularly due to the rapid evolution of organic-inorganic bio-hybrid PDs (Bio-HPDs). This report presents a significant photoresponse of the bioinspired graphene-based PD fabricated with deoxyribonucleic acid-cetyltrimetylammonium chloride (DNA-CTMA) biomolecules on the n-type GaN substrate. Bio-HPDs respond to the infrared, visible, and ultraviolet wavelengths. Moreover, the Bio-HPDs show photosensitivities (Iphoto/Idark) of 21, 143, and 1194 for infrared, visible, and ultraviolet wavebands, respectively, which can be attributed to the integration of high-mobility graphene and photosensitive DNA-CTMA biomolecules. In addition, the corresponding charge transfer mechanisms in the PDs are explained by energy band diagrams.

The chemical, structural and electrical characteristics of a fabricated Au/Gd2O3/n-GaN heterostructure with gadolinium oxide (Gd2O3) as an insulating layer are explored by XPS, XRD and I–V techniques at room temperature and 400 °C annealing. XPS and XRD results reveal that the Gd2O3 films are formed at the interface. The electrical results of heterostructure are correlated with the conventional Au/n-GaN Schottky structure results. The as-deposited and 400 °C annealed heterostructures exhibited excellent rectifying behavior and very low reverse leakage current compared to the Schottky structure. Higher barrier height (BH) and on/off ratio are achieved for the heterostructure compared to the Schottky structure, which has led the barrier height modified by Gd2O3 insulating layer. Also, the results indicate that the BH slightly increases for the 400 °C annealed heterostructures. Further, the BH, ideality factor and series resistance are evaluated by Cheung’s, Norde functions and ΨS-V plot and the values are found to be similar with one another that indicates their consistency and validity. In addition, the mechanism of the BH modulation could be explained by feasible energy level band diagrams. These findings indicate that the Gd2O3 films could be a favored dielectric material for the development of metal/insulating/semiconductor devices.

We demonstrated dual-surface modification of GaN/AlGaN/GaN high-electron mobility transistors using tetramethylammonium hydroxide (TMAH) and piranha solutions prior to gate metallization. The TMAH-treated device exhibits improved performances with lower I-V hysteresis, in off-state leakage current and gate leakage current. The device performances were further significantly improved with applies additional piranha solution treatment right after the TMAH treatment, especially in hysteresis and 1/f-noise characteristics. It is found that the Schottky barrier height is high and ideality factor is low measured from I-V characteristics for the TMAH and piranha solution treated device. Reasonable gate leakage mechanisms were also discussed using Poole-Frenkel and Schottky emissions. In addition, it is observed that the magnitude of interface state density for the TMAH treatment after the piranha solution treated device shows significantly low compared to other devices. These excellent device-performances are observed due to the reason of dual-surface treatment which effectively decreases the surface trap density with an appropriate etching and passivation of the device surface exposed prior to the gate metallization.

Nowadays, diluted magnetic semiconductors with improved ferromagnetic feature is utterly seeking for use in modern spintronic applications.We describe the optical as well as magnetic properties of CdS, CdS:Cr, CdS:(Cr + Al), and CdS:(Cr + Mn) co-doped samples. The substitution of Cr dopant and co-dopant ions (Al and Mn) in the host sites were confirmed through structural analysis. Declining of energy band gap with the incorporation of Cr dopant and co-dopant ions (Al and Mn) into the CdS host lattice was estimated through optical studies. Room-temperature magnetic hysteresis curves revealed that pure CdS exhibited paramagnetic nature due to its surface defects, whereas CdS:Cr, CdS:(Cr + Al), and CdS:(Cr + Mn) co-doped nanoparticles showed better ferromagnetic characteristics. Among all synthesized nanoparticles, CdS:(Cr + Al) semiconductor sample exhibited enhanced ferromagnetic nature and may benficial for spintronic applications.

Recently, considerable interest have occurred in the development of an organic-inorganic-based bio-hybrid photodiodes (Bio-HPDs) with metal-free, eco-friendly, and cost-competitive features for light-sensitive devices. This paper reports a bio-inspired optical absorber material for the fabrication of Bio-HPDs using n-type hydrogenated amorphous silicon (a-Si:H) and a natural deoxyribonucleic acid (DNA)-cetyltrimethylammonium chloride (CTMA) biomaterial. a-Si:H is inexpensive and abundant, and DNA-CTMA is metal-free and eco-friendly. A DNA-CTMA coating on n-type a-Si:H leads to a chemically stable material with increased absorption and effective ties of dangling bonds and interface state density. Analysis results showed that the rectification ratio (RR) of the Bio-HPD is found to be 4 times higher than reference PD. This indicates that the effective RR is improved by the DNA-CTMA layer since it creates molecular charge interactions between DNA-CTMA layer and a-Si:H substrate. Moreover, Bio-HPD shows a light photosensitivity (Iphoto/Idark) of 474 with more reliable and has longer life time. In addition, the formation and feasible charge transport mechanisms are discussed. This biomaterial can be used for the development of commercially viable and environmentally safe large-scale Bio-HPDs applications.

A deoxyribonucleic acid-cetyltrimethylammonium chloride (DNA-CTMA) biopolymer-based inorganic p-type GaN bio-hybrid Schottky photodiode was fabricated and its electrical characteristics were studied. The Al/Cr/DNA-CTMA/p-GaN bio-hybrid photodiode parameters were investigated using current-voltage (I-V), capacitance-voltage-frequency (C-V-f) and conductance-voltage-frequency (G/ω-V-f) measurements. The calculated ideality factor and barrier height of the diode were found to be 1.8 and 0.82 eV, respectively. The electrical and photo-conduction properties of the diode were examined using dark I-V and steady-state photoconductivity techniques. The C-V-f and G/ω-V-f measurements showed that the capacitance and conductance of the diode depends on the bias voltage and frequency, respectively. On the other hand, a decrease in capacitance and increase in conductance with increasing frequency at room temperature were demonstrated based on the interface state density. In addition, the interface state density decreased exponentially with increasing frequency. It is also noted that series resistance decreased with increasing frequency. The results showed that the biopolymer-based Al/Cr/DNA-CTMA/p-GaN bio-hybrid photodiode can be used as a photosensor in optical applications and the development of high-performance organic-inorganic-based p-Schottky diodes that are environmentally safe.

In this work, a deoxyribonucleic acid-cetyltrimethylammonium chloride (DNA-CTMA) biomaterial based p-type hydrogenated amorphous silicon (a-Si:H) photodiode (PD) is fabricated and its electrical characteristics are investigated. The Al/DNA-CTMA/p-type a-Si:H PD parameters are studied using current-voltage (I-V), capacitancevoltage-frequency (C-V-f) and conductance-voltage-frequency (G/ω-V-f) measurements. The barrier height and the ideality factor of the diode are found to be 0.78 eV and 1.9, respectively. The electrical and photoconductivity properties of the diode are analyzed by using dark I-V and transient photocurrent techniques. The C-V-f and G/ω-V-f measurements indicate that the capacitance and conductance of the diode depend on the voltage and frequency, respectively. The experimental results reveal that the decreases in capacitance and the increases in conductance with an increase in frequency can be explained on the basis of interface states (NSS). Series resistance (RS) measurements are performed on the diode and discussed here. The obtained electrical parameters confirm that the Al/DNA-CTMA/p-type a-Si:H PD can be used as an optical sensor for the development of commercial applications that are environmentally benign.

This paper reviews the electrical and transport properties of Ti/polyvinylpyrrolidone (PVP)/p-InP metal/interlayer/semiconductor (MIS) Schottky diode and compared its results with the Ti/p-InP metal/semiconductor (MS) diode. Analysis results showed that the barrier height (BH) and ideality factor of the MIS diode are found to be improved compared to the MS diode. This indicates that the effective BH is modified by the PVP interlayer since it creates physical barrier between the Ti metal and the p-InP substrate. It is noted that the evaluated BH by Cheung’s and ψS-V plots is in good concurrence with one another. Also, the series resistance of the MS and MIS diodes is estimated by Cheung’s functions. The insertion of the PVP interlayer led to a decrease of the interface state density in the Ti/p-InP MS diode. In addition, the relevant junction mechanisms are explained by feasible energy level band diagrams. The Poole–Frenkel emission is the governing conduction mechanism in the Ti/p-InP MS diode. However, at lower voltage region the Poole–Frenkel is conquered, whereas at higher voltage region the Schottky emission is occupied for the Ti/PVP/p-InP MIS diode.

The structural, chemical, electrical and carrier transport properties of high-k ZrO 2 on n-type InP with Au electrode have been studied by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) , current-voltage (I V) and capacitance-voltage (C V) techniques at room temperature. Results show that the high barrier height is achieved for the Au/ZrO 2 /n-InP metal-insulator-semiconductor (MIS) diode as compared to the Au/n-InP metal-semiconductor (MS) diode. Using Cheung's functions, the barrier height, ideality factor and series resistance are estimated for the MS and MIS diodes. The barrier heights are determined by I V, Cheung's and surface potential-forward voltage plot for both the MS and MIS diodes which are found to be in good agreement with each other. Results indicate that the interface state density of Au/ZrO 2 /n-InP MIS diode is lower than that of Au/n-InP MS diode. This may be attributed to the fact that the introduction of the high-k ZrO 2 interlayer led to reduction of the interface state density in the Au/n-InP MS diode. Results indicate that the Poole-Frenkel emission is the dominant conduction mechanism in the lower bias region while Schottky emission is dominant in the higher bias region for both the Au/n-InP MS and Au/ZrO 2 /n-InP MIS diodes.

This work demonstrates the modification of electrical parameters of the Au/n-GaN Schottky junction (SJ) by a thin magnetite metal (Fe3O4) interlayer in between the Au and n-GaN substrates. The current–voltage (I–V), voltage-dependent capacitance–frequency (C–f) and conductance–frequency (G–f) characteristics of the Au/Fe3O4/n-GaN heterojunction (HJ) are systematically studied. Using statistical analysis, the mean barrier heights and ideality factors are found to be 0.70 eV and 1.62 for the SJ and 0.84 eV and 1.87 for the HJ, respectively. It is noticed that the mean barrier height of Au/Fe3O4/n-GaN HJ increases as compared that of the Au/n-GaN SJ, indicating the Fe3O4 interlayer modified the barrier height. The SJ revealed a transition from Poole–Frenkel emission at low voltages to Schottky emission at high voltages. However, the HJ exhibited Schottky emission over whole voltage range. It is observed that the higher values of capacitance decrease at low frequencies that are attributed to the excess capacitance resulting from the interface states in equilibrium with the n-GaN which could respond the ac signal. The interface states density (NSS) and relaxation time (τ) of the Au/Fe3O4/n-GaN HJ are estimated from C–f plots, respectively. The NSS reveals that the interface states decrease with voltage from the bottom of the conduction band toward the mid-gap.

International audience; Two different lateral GaN-based nanowire gate-all-around transistors with and without 2-D electron gas (2-DEG) channel were fabricated using top-down approach, and their noise characteristics were investigated. The nanowire transistor with 2-DEG channel had a relatively larger channel cross section, which consists of regrown AlGaN/GaN plateau on the trapezoidal GaN layer, and exhibited negative threshold voltages ( ${V} _{\textsf {th}}$ ). The transistor without 2-DEG channel consisted only GaN layer with triangular-shaped smaller channel cross section and exhibited a positive ${V} _{\textsf {th}}$ . Both nanowire transistors clearly demonstrated typical $1/{f}$ noise characteristics, but the AlGaN/GaN nanowire transistor with 2-DEG channel showed larger noise magnitude. The noise characteristics of both devices are well explained by the carrier number fluctuation with correlated mobility fluctuation model. Using this model, the interface trap densities and the remote Coulomb scattering parameters were extracted, revealing a worse interface quality for the AlGaN/GaN device on the one hand, but stronger scattering for the narrow GaN transistor on the other hand.

The creation of oxide based magnetic materials has attracted a great deal of scientific attention, owing to their novel applications in optoelectronic, memory, and spintronic device applications. In this study, the authors report upon the structural, optical, and magnetic properties of Co-substituted CeO2 nanocrystals synthesized via the wet chemical precipitation method. The obtained nanoparticles show good crystallinity as well as an FCC structure with an Fm3m space group of host CeO2 lattice, as confirmed by an X-ray diffraction results. It is noted that Co substitution at low concentrations enhances the photoluminescence characteristics of CeO2 nanoparticles, while higher concentrations significantly reduce the intensity of PL emission, as revealed by PL studies. The estimated M − H loops illustrate that pristine CeO2 shows a paramagnetic nature, while all Co-substituted samples were ferromagnetic in nature. Furthermore, magnetic parameters such as saturation magnetization (MS) and residual magnetization (MR) increased with the inclusion of Co content, reaching a maximum at 4 at% Co and quenching at 6 at% and 8 at% of Co-substitution. In particular, Ce1-xCoxO2 (x = 0.04) nanoparticles show better luminescence and magnetic characteristics than the remaining concentrations.

The temperature-dependent electrical properties and carrier transport mechanisms of tetramethylammonium hydroxide (TMAH)-treated Ni/Au/Al2O3/GaN metal–insulator–semiconductor (MIS) diodes have been investigated by current–voltage (I–V) and capacitance–voltage (C–V) measurements. The experimental results reveal that the barrier height (I–V) increases whereas the ideality factor decreases with increasing temperature. The TMAH-treated Ni/Au/Al2O3/GaN MIS diode showed nonideal behaviors which indicate the presence of a nonuniform distribution of interface states (N SS) and effect of series resistance (R S). The obtained R S and N SS were found to decrease with increasing temperature. Furthermore, it was found that different transport mechanisms dominated in the TMAH-treated Ni/Au/Al2O3/GaN MIS diode. At 150 K to 250 K, Poole–Frenkel emission (PFE) was found to be responsible for the reverse leakage, while Schottky emission (SE) was the dominant mechanism at high electric fields in the temperature range from 300 K to 400 K. Feasible energy band diagrams and possible carrier transport mechanisms for the TMAH-treated Ni/Au/Al2O3/GaN MIS diode are discussed based on PFE and SE.

The electrical and carrier transport properties of Au/Pr6O11/n-GaN metal/interlayer/semiconductor (MIS) structure with an electron beam deposited high-k rare-earth oxide as an interlayer have been investigated in the temperature range of 270–420 K. The electrical characteristics such as current–voltage (I–V), turn-on voltage and series resistance (RS) are analyzed at different temperatures. These analysis showed that the obtained barrier heights (Φb) increase while ideality factor (n) and RS decrease with increasing temperature. The characteristic temperature (T0) is determined from the RS against temperature plots, and the value (T0) is well matched with each other. The calculated thermal coefficient (Kj) value is – 2.1 mV/K at ≥ 270 K. The obtained effective barrier height (1.22 eV) is consistent with the theoretical value. The temperature-dependent ideality factor values are in good agreement with characteristic energy of 31 meV. The estimated interface state density (NSS) increases with decreasing temperature that could be associated with the molecular restructuring and reordering of the Pr6O11/n-GaN interface. The reverse bias results showed that the current conduction is dominated by Poole-Frenkel emission in the temperature range of 270–330 K while the Schottky emission is dominated in the temperature range of 360–420 K.

This work explores the temperature-dependent electrical characteristics and carrier transport mechanism of Au/p-Cu2ZnSnS4/n-type GaN heterojunction (HJ) diodes with a CZTS interlayer. The electrical characteristics were examined by current–voltage–temperature, turn-on voltage–temperature and series resistance–temperature in the high-temperature range of 300–420 K. It is observed that an exponential decrease in the series resistance (RS) and increase in the ideality factor (n) and barrier height (ϕb) with increase in temperature. The thermal coefficient (Kj) is determined to be − 1.3 mV K−1 at ≥ 300 K. The effective ϕb is determined to be 1.21 eV. This obtained barrier height is consistent with the theoretical one. The characteristic temperature (T0) resulting from the Cheung’s functions [dV/d(lnI) vs. I and H(I) vs. I], is seen that there is good agreement between the T0 values from both Cheung’s functions. The relevant carrier transport mechanisms of Au/p-CZTS/n-type GaN HJ are explained based on the thermally decreased energy band gap of n-type GaN layers, thermally activated deep donors and increased further activated shallow donors.

The electrical properties and carrier transport mechanism of vanadium (V) Schottky contacts on p-type GaN have been investigated. The electrical characteristics are analyzed by using current–voltage–temperature, turn-on voltage–temperature and series resistance–temperature in the temperature range of 280–400 K. An exponential decrease in the experimental series resistance ( R S ) and increase in the ideality factor ( n ), Schottky barrier height (SBH) with decrease in the temperature is observed. The characteristic temperature ( T 0 ) resulting from the Norde’s function is compared with those from the Cheung’s functions, and it is observed that there is good agreement between the T 0 values from both methods. Experimental results reveal that the thermal coefficient ( K j ) is −1.0 mV/K at ⩾280 K. The effective SBH is determined to be 1.88 ± 0.2 eV, which is in good agreement with the theoretical value. The feasible carrier transport mechanism of V/p-GaN Schottky diode is discussed based on the thermally decreased energy band gap of p-type GaN layers, thermally increased deep-level acceptor and increased further activated shallow-level acceptor.

We demonstrated high-performance GaN-based light-emitting diodes (LEDs) with hierarchical m-plane nano-prism light extractors on the n-GaN mesa sidewalls by using a tetramethylammonium hydroxide (TMAH)-based crystallographic etching technique. The crystallographic etching method leads to a chemically stable formation of hierarchical m-plane nano-prism structures as light extractors, increased p-carriers near the p-GaN surface, and the effective removal of the native oxides on the p-GaN surface. These results lead to considerable improvement of the p-ohmic contact properties between the p-GaN layer and the ITO electrode, remarkable device-performance characteristics, an improved efficiency droop, and a longer device lifetime. Based on the device-performance and the p-ohmic contact data, the hierarchical m-plane nano-prism structure acts as a multifunctional factor exhibiting high-efficiency photon-extraction, strong packaging effects, strong suppression of the leakage current along the sidewalls from the p-GaN to the n-GaN, and/or a partial release of the piezoelectric field across the quantum well region.

NiO-Ag thin films were deposited on Corning 7059 glass substrates by DC reactive magnetron sputtering technique and investigated the substrate temperature (Ts) dependent properties of NiO-Ag thin films. X-ray diffraction results showed that crystalline films can be obtained at high Ts and all films have a preferred crystal growth texture with face centered cubic (fcc) structure and was also confirmed by Raman studies. The grain size, transmittance, band gap, mobility and carrier concentrations were increased with Ts. Room temperature deposited films have an average roughness around 6.9 nm where as increment of Ts resulted in increased roughness up to 14 nm with nanocrystalline morphology. The optimum substrate temperature to obtain NiO-Ag films was found to be 200°C. It was found that with increasing the Ts, resistivity of the films was significantly decreased.

The electrical characteristics and reverse leakage mechanisms of tetramethylammonium hydroxide (TMAH) surface-treated Ni/Au/Al2O3/GaN metal-insulator-semiconductor (MIS) diodes were investigated by using the current-voltage (I–V) and capacitance-voltage (C–V) characteristics. The MIS diode was formed on n-GaN after etching the AlGaN in the AlGaN/GaN heterostructures. The TMAH-treated MIS diode showed better Schottky characteristics with a lower ideality factor, higher barrier height and lower reverse leakage current compared to the TMAH-free MIS diode. In addition, the TMAH-free MIS diodes exhibited a transition from Poole-Frenkel emission at low voltages to Schottky emission at high voltages, whereas the TMAH-treated MIS diodes showed Schottky emission over the entire voltage range. Reasonable mechanisms for the improved device-performance characteristics in the TMAH-treated MIS diode are discussed in terms of the decreased interface state density or traps associated with an oxide material and the reduced tunneling probability.

The effect of tetramethylammonium hydroxide (TMAH) treatment on the electrical properties of Ni/Au/GaN Schottky diodes have been investigated by current–voltage ( I – V ) and capacitance–voltage ( C – V ) techniques. The barrier heights and ideality factors measured from I – V characteristics are found to be 0.70 eV and 1.32 for without TMAH treatment, and 0.78 eV and 1.14 for with TMAH treatment, respectively. Cheung method is used to measure the series resistance and barrier height of the Schottky diodes, and the barrier height consistency is checked using the Norde method. The magnitude of interface state density for the diodes without and with TMAH treatment are varied from 7.45 × 10 13 eV −1 cm −2 to 6.09 × 10 12 eV −1 cm −2 and 4.03 × 10 13 eV −1 cm −2 to 1.79 × 10 12 eV −1 cm −2 in the below the conduction band from E C -0.19 eV to E C -0.63 eV and E C -0.22 eV to E C -0.73 eV. Based on the results, the TMAH treatment effectively removes of surface oxide (Ga x O y ) layer, formed due to the incorporation of the residual oxygen with Ga atom at the GaN surface during the plasma etching. The decrease in interface state density at the Ni/Au/GaN interface could be the reason for the improvement in the electrical properties.

We have investigated the electrical properties of Ru/Ni/n-GaN Schottky structure using current-voltage (I-V) and capacitance-voltage (C-V) measurements at room temperature. The barrier height (Fbo) and ideality factor (n) of Ru/Ni/n-GaN Schottky structure are found to be 0.66 eV and 1.44, respectively. The Fbo and the series resistance (RS) obtained from Cheung's method are compared with modified Norde's method, and it is seen that there is a good agreement with each other. The energy distribution of interface state density (NSS) is determined from the I-V measurements by taking into account the bias dependence of the effective barrier height. Further, the interface state density NSS as determined by Terman's method is found to be 2.14´10 12 cm -2 eV -1 for the Ru/Ni/n-GaN diode. Results show that the interface state density and series resistance has a significant effect on the electrical characteristics of studied diode.

We report on the effect of an annealing temperature on the electrical properties of Au/Ta2O5/n-GaN metal–insulator–semiconductor (MIS) structure by current–voltage (I–V) and capacitance–voltage (C–V) measurements. The measured Schottky barrier height (Φ bo) and ideality factor n values of the as-deposited Au/Ta2O5/n-GaN MIS structure are 0.93 eV (I–V) and 1.19. The barrier height (BH) increases to 1.03 eV and ideality factor decreases to 1.13 upon annealing at 500 ∘C for 1 min under nitrogen ambient. When the contact is annealed at 600 ∘C, the barrier height decreases and the ideality factor increases to 0.99 eV and 1.15. The barrier heights obtained from the C–V measurements are higher than those obtained from I–V measurements, and this indicates the existence of spatial inhomogeneity at the interface. Cheung’s functions are also used to calculate the barrier height (Φ bo), ideality factor (n), and series resistance (R s ) of the Au/Ta2O5/n-GaN MIS structure. Investigations reveal that the Schottky emission is the dominant mechanism and the Poole–Frenkel emission occurs only in the high voltage region. The energy distribution of interface states is determined from the forward bias I–V characteristics by taking into account the bias dependence of the effective barrier height. It is observed that the density value of interface states for the annealed samples with interfacial layer is lower than that of the density value of interface states of the as-deposited sample.

The effect of annealing temperature on interface properties of iridium/ruthenium (Ir/Ru) Schottky contacts on n-type InGaN have been investigated by current–voltage (I–V), capacitance–voltage (C–V), Auger electron spectroscopy (AES) and X-ray diffraction (XRD) techniques. An as-deposited Ru/Ir/n-InGaN Schottky diode exhibits a barrier height of 0.61 eV (I–V) and 0.79 eV (C–V), which increases to 0.71 eV (I–V) and 0.96 eV (C–V) after annealing at 200 °C. A maximum barrier height of 0.73 eV (I–V) and 1.02 eV (C–V) is achieved for the Ir/Ru Schottky contacts after annealing at 300 °C. Further, it is observed that the Schottky barrier height slightly decreases upon annealing at temperatures of 400 °C and 500 °C and the obtained values are 0.68 eV (I–V), 0.93 eV (C–V) and 0.66 eV (I–V), 0.86 eV (C–V), respectively. The Norde and Cheung’s methods are used to extract the barrier height (Φb), ideality factor (n) and series resistance (Rs). The interface state density is also determined by Terman’s method. According to the above results, the optimum annealing temperature for Ru/Ir/n-InGaN Schottky diode is 300 °C. Based on the AES and XRD analysis, the formation of gallide phases at the Ru/Ir/n-InGaN interface could be the reason for the increase of Schottky barrier heights upon annealing temperatures. It is noted that overall surface morphology of Ir/Ru Schottky contacts is reasonably smooth even after annealing at 500 °C as observed from AFM results.

The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Ni/Cu/n-InP Schottky barrier diodes are studied over a wide temperature range, from 210 K to 420 K. The I-V characteristics display anomalous thermal behavior. The apparent barrier height decays, and the ideality factor grows at low temperatures, and the series resistances resultingfromCheung'sandNorde'sproceduresaremarkedly temperature dependent. The nonlinearity of the Richardson plot and the strong temperature dependence of the Schottky- barrier parameters indicate that the interface is spatially inho- mogeneous. Plots of the zero-bias barrier height as a function of 1/(2kT) points to a Gaussian distribution of barrier heights with 0.90 eV mean height and 0.014 eV standard deviation. When this distribution is accounted for, a Richardson of 6.5 A/(cm K) 2 results, relatively close to the 9.4/(cm K) 2 predicted by theory. We conclude that, combined with a Gaussian distribution of barrier heights, the thermionic- emission mechanism explains the temperature-dependent I-V and C-V characteristics of the studied Schottky-barrier diodes.

Recently, significant advances have occurred in the development of phosphors for bio hybrid light-emitting diodes (Bio-HLEDs), which have created brighter, metal-free, rare-earth phosphor-free, eco-friendly, and cost-competitive features for visible light emission. Here, we demonstrate an original approach using bioinspired phosphors in Bio-HLEDs based on natural deoxyribonucleic acid (DNA)-curcumin complexes with cetyltrimethylammonium (CTMA) in bio-crystalline form. The curcumin chromophore was bound to the DNA double helix structure as observed using field emission tunnelling electron microscopy (FE-TEM). Efficient luminescence occurred due to tightly bound curcumin chromophore to DNA duplex. Bio-HLED shows low luminous drop rate of 0.0551 s−1. Moreover, the solid bio-crystals confined the activating bright luminescence with a quantum yield of 62%, thereby overcoming aggregation-induced quenching effect. The results of this study herald the development of commercially viable large-scale hybrid light applications that are environmentally benign.

The effects of thermal annealing on electrical and structural characteristics of iridium (Ir) Schottky contacts to n-type InGaN have been studied using current–voltage (I–V), capacitance–voltage (C–V), secondary ion mass spectrometer (SIMS), and X-ray diffraction (XRD) measurements. Measurements showed that the Schottky barrier height (SBH) of as-deposited sample is 0.79 eV (I–V) and 1.07 eV (C–V). It is observed that the barrier height increases to 0.85 eV (I–V) and 1.21 eV (C–V) after annealing at 300 °C for 1 min in N2 ambient. However, it is found that the SBH slightly decreases when the contacts are annealed at 400 and 500 °C and the corresponding values are 0.84 eV (I–V), 1.17 eV (C–V) for 400 °C and 0.80 eV (I–V), 1.11 eV (C–V) for 500 °C, respectively. Using Cheung's functions, the barrier height (Φb), ideality factor (n), and series resistance (Rs) are also calculated. From the above results, it is clear that the optimum annealing temperature for Ir Schottky contact is 300 °C. SIMS and XRD results shows that the formation of gallide phases at Ir/n-InGaN interfaces could be the reason for variation in the SBHs upon annealing at elevated temperatures. Atomic force microscopy (AFM) results show that the overall surface morphology of Ir Schottky contacts on n-InGaN stays reasonably smooth. These results make Ir Schottky contacts attractive for high-temperature device applications.

In the present work, thin film of polyvinyl alcohol (PVA) is fabricated on n-type InP substrate as an interfacial layer for electronic modification of Au/n-InP Schottky contact. The electrical characteristics of Au/PVA/n-InP Schottky diode are determined at annealing temperature in the range of 100–300 °C by current–voltage (I-V) and capacitance–voltage (C-V) methods. The Schottky barrier height and ideality factor (n) values of the as-deposited Au/PVA/n-InP diode are obtained at room temperature as 0.66 eV (I-V), 0.82 eV (C-V) and 1.32, respectively. Upon annealing at 200 °C in nitrogen atmosphere for 1 min, the barrier height value increases to 0.81 eV (I-V), 0.99 eV (C-V) and ideality factor decreases to 1.18. When the contact is annealed at 300 °C, the barrier height value decreases to 0.77 eV (I-V), 0.96 eV (C-V) and ideality factor increases to 1.22. It is observed that the interfacial layer of PVA increases the barrier height by the influence of the space charge region of the Au/n-InP Schottky junction. The discrepancy between Schottky barrier heights calculated from I-V and C-V measurements is also explained. Further, Cheung's functions are used to extract the series resistance of Au/PVA/n-InP Schottky diode. The interface state density as determined by Terman's method is found to be 1.04 × 10 12 and 0.59 × 10 12 cm − 2 eV − 1 for the as-deposited and 200 °C annealed Au/PVA/n-InP Schottky diodes. Finally, it is seen that the Schottky diode parameters changed with increase in the annealing temperature.

The temperature-dependent electrical properties of Au/SiO 2 /n-GaN metal-insulator-semiconductor (MIS) structure have been investigated in the temperature range of 120–390 K. Anomalous strong temperature dependencies of the barrier height ( Φ bo ), ideality factor ( n ), interface state density ( N SS ) and series resistance ( R S ) are obtained. Such behaviour is attributed to barrier inhomogeneities by assuming a Gaussian distribution of barrier heights (GD BHs) at the interface. It is evident that the diode parameters such as zero-bias barrier height increases and the ideality factor decreases with increasing temperature. The values of series resistance that are obtained from Cheung’s method is decreasing with increasing in temperature. The temperature-dependent current–voltage characteristics of the MIS diode have been shown a double Gaussian distribution giving mean barrier heights of 0.38 eV and 1.06 eV and standard deviations of 0.0561 and 0.2742 V, respectively. A modified ln ( I o / T 2 ) − q 2 σ o 2 /2 k 2 T 2 versus 10 3 /T plot for the two temperature regions gives φ b o ¯ and A ∗ as 0.55 eV and 11.56 A cm −2 K −2 , and 1.02 eV and 23.48 A cm −2 K −2 respectively. The Interface state density values are calculated by I–V and C–V measurements at different temperatures using Terman’s method. It is observed that the interface state density decreases with increase in temperature (120–390 K). Therefore, it has been concluded that the temperature dependence of the forward I–V characteristics of the Au/SiO 2 /n-GaN Schottky diodes can be explained with a double GD of the BHs.

In the present work, we have investigated the current–voltage ( I – V ) and capacitance–voltage ( C – V ) characteristics of Au/SiO 2 /n-GaN metal–insulator–semiconductor (MIS) Schottky diode and compared with Au/n-GaN metal–semiconductor (MS) Schottky diode. Calculations showed that the Schottky barrier height and ideality factor of the MS Schottky diode is 0.79 eV ( I – V ), 0.87 eV ( C – V ) and 1.45, respectively. It is observed that the Schottky barrier height increases to 0.86 eV ( I – V ), 0.99 eV ( C – V ) and ideality factor deceases to 1.3 for MIS diode. For the MS diode, the calculated doping concentration is 4.17 × 10 17 cm −3 . However, in the case of the MIS Schottky diode, the decrease in doping concentration is observed and the respective value is 2.08 × 10 17 cm −3 . The obtained carrier concentration of the MIS diode is reduced about 50% when compared to the MS diode. The interface state density as determined by Terman's method is found to be 3.79 × 10 12 and 3.41 × 10 10 cm −2 eV −1 for the MS and MIS Schottky diodes, respectively. The calculated interface densities are 2.47 × 10 11 cm −2 eV −1 , 3.35 × 10 11 cm −2 eV −1 and 3.5 × 10 11 cm −2 eV −1 for the sweep rates of 300, 450 and 600 mV/s from MOS C – V measurements for the MIS Schottky diode. The interface state density calculated from Terman's method is found to be increased with sweep rate. From the C – V measurement, it is noted that the decrease in the carrier concentration in MIS diodes as compared to MS diode may be due to the presence of oxide interfacial layer. DLTS measurements have also been performed on MIS Schottky diode and discussed.