Search

Currently, halide perovskites with exceptional properties are the most suitable candidates for RRAM devices. In the present study, a comprehensive investigation of structural, mechanical, optoelectronic and thermoelectric properties of Cs2BSnX6 (B = Mg, Cu; X = Cl, Br, I) has been conducted for the potential application in resistive switching random access memory (RRAM) devices. Mechanical properties display that studied perovskites exhibit mechanical stability and ductile behavior with an anisotropic character. A comparison of band structure using PBE-GGA, and TB-mBJ was also made. The band structure with TB-mBJ investigation disclosed that Cs2MgSnCl6, Cs2MgSnBr6, Cs2MgSnI6, Cs2CuSnCl6, Cs2CuSnBr6, and Cs2CuSnI6 have indirect bandgaps with value of 3.64 eV, 2.87 eV, 2.05 eV, 2.30 eV, 1.50 eV and 0.90 eV respectively. These values are found to be slightly more than PBE-GGA approximations. The optical investigation illustrates that Cs2CuSnI6 can absorb a wide range of electromagnetic radiation wavelengths from ultraviolet to infrared, making it the optimal candidate for RRAM devices. Thermoelectric properties show electrical conductivity values of the 1.65 × 1019, 1.61 × 1019, 1.58 × 1019, 1.95 × 1019, 2.35 × 1019, 2.40 × 1019 (Ω.m.s)−1 for Cs2MgSnCl6, Cs2MgSnBr6, Cs2MgSnI6, Cs2CuSnCl6, Cs2CuSnBr6, and Cs2CuSnI6 respectively at 1500 K. Furthermore, the calculated optical and thermoelectric properties of Cs2BSnX6 (B = Mg, Cu; X = Cl, Br, I) compared with previously studied Cs2CaSnX6 (X = Cl, Br, I), disclosing that Mg and Cu-based perovskites display better optical and thermoelectric properties. The vital findings of this study express that Cs2CuSnI6 is the most appropriate candidate for less-energy consuming RRAM devices among all studied perovskites. [ABSTRACT FROM AUTHOR]

The non-toxic nature, low cost, and excellent optical properties make oxide-based perovskites potential candidates for solar cell applications. The full potential linearized augmented plane wave approach is applied to explore the structural, electronic, optical, and thermoelectric properties of Ba2XTiO6 (X = Hf, Ce, and Te) for solar cell applications. As demonstrated by an elastic study, Ba2HfTiO6 is brittle, while Ba2CeTiO6 and Ba2TeTiO6 are ductile. The anisotropic values of Ba2HfTiO6, Ba2CeTiO6 and Ba2TeTiO6 are 1.14, 0.67 and 0.80 respectively. The electronic bandgap values of Ba2HfTiO6, Ba2CeTiO6, and Ba2TeTiO6 are computed as 3.44 eV, 2.96 eV, and 1.26 eV using the Tran-Blaha-modified Becke–Johnson approach. Moreover, the bandgap of Ba2TeTiO6 is compatible for solar cell applications. Optical investigation demonstrates that Ba2TeTiO6 shows maximum absorption in visible light among the studied perovskites. Lastly, the transport properties exhibit figure of merit values of 0.73, 0.77 and 0.81 for Ba2HfTiO6, Ba2CeTiO6, and Ba2TeTiO6 respectively. Consequently, with the bandgap falling in the visible region and high figure of merit among the studied perovskites, Ba2TeTiO6 emerges as the most suitable candidate for solar cell applications based on its electronic, optical, and thermoelectric properties. [ABSTRACT FROM AUTHOR]

The Density Functional Theory (DFT) calculations interpreted the electronic and optical alteration of Ruddlesden–Popper layered perovskite (Sr3Zr2O7) with substitutional doping of Ti‐, Hf‐, and Ti+Hf‐ atoms in place of Zr‐atoms by generating the oxygen vacancies (Vos) defect. Formation energy and phonon calculations confirmed that the studied composites are dynamically stable, and the lattice parameters of the considered RP perovskite with and without vacancy defects did not change by introducing a small concentration of doped elements. The doped Sr3Zr2O7 composites show band gap tuning in the presence and absence of Vos, which was 3.31 eV in pristine form, and localized states near the Fermi line due to dopant and Vos, which confirmed the quantized conductance in all composites and may be beneficial for overcoming uniformity issues in nonvolatile memory devices. Isosurface charge density calculations also verified this result by depicting the physical mechanism of charge accumulation and depletion in the layers of RP perovskite in the vicinity of defects, resulting in residual conducting filaments guiding its growth and leading it to a low resistance state. The photosensitive response of this layered perovskite also confirmed its use for memory storage applications. The valuable outcomes of this study predicted that Sr3Zr2O7+Ti+Hf is the most stable and, hence, the best composite for nonvolatile RRAM device applications. [ABSTRACT FROM AUTHOR]

Hybrid lead halide perovskites have been considered as promising candidates for a large variety of optoelectronic applications. By exploring novel combinations of lead-free double perovskite halides, it is possible to find a suitable replacement for poisonous lead halide perovskites, enhancing electronic and optical response for their application as optically-influenced resistive switching random access memory (RRAM). In this work, the structural, mechanical, elastic, electronic, optical, and thermoelectric characteristics of lead-free double halide perovskites were investigated by Vienna ab initio simulation package (VASP) to explore their role in RRAM. From the analysis of mechanical constraints, it is clear that all three composites of Cs 2 CaSnX 6 (X = Cl, Br, I) are mechanically stable and ductile in nature. The electronic bandgap with and without spin-orbit coupling (SOC), and total and sub-total density of states (TDOS, sub-TDOS) have been calculated using the Perdew-Burke-Ernzerhof generalized gradient approximation (PBE-GGA) potentials. The observed direct band gaps of 3.58 eV, 3.09 eV, and 2.60 eV for Cs 2 CaSnCl 6 , Cs 2 CaSnBr 6 , and Cs 2 CaSnI 6 , respectively, reveal the suitability of these specified composites as resistive switching material for RRAM devices. Additionally, the optical characteristics, such as complex refractive index, absorption coefficient, and reflectivity of the compounds under consideration have been calculated under the action of incident photons of 0 to 14 eV energy. The thermoelectric properties of Cs 2 CaSnX 6 (X = Cl, Br, I) double perovskite halide were computed and analyzed with the help of the BoltzTraP Code., Competing Interests: The authors declare that there are no conflicts of interest., (This journal is © The Royal Society of Chemistry.)

Atomic Layer Deposition (ALD) was used for a tri-layer structure (HfO 2 /Al 2 O 3 /HfO 2 ) at low temperature over an Indium Tin Oxide (ITO) transparent electrode. First, the microstructure of the fabricated TaN/HfO 2 /Al 2 O 3 /HfO 2 /ITO RRAM device was examined by the cross-sectional High-Resolution Transmission Electron Microscopy (HRTEM). Then, Energy Dispersive X-ray Spectroscopy (EDS) was performed to probe compositional mapping. The bipolar resistive switching mode of the device was confirmed through SET/RESET characteristic plots for 100 cycles as a function of applied biasing voltage. An endurance test was performed for 100 DC switching cycles @0.2 V wherein; data retention was found up to 10 4 s. Moreover, for better insight into the charge conduction mechanism in tri-layer HfO 2 /Al 2 O 3 /HfO 2 , based on oxygen vacancies (V OX ), total density of states (TDOS), partial density of states (PDOS) and isosurface three-dimensional charge density analysis was performed using WEIN2k and VASP simulation packages under Perdew-Burke-Ernzerhof _Generalized Gradient approximation (PBE-GGA). The experimental and theoretical outcomes can help in finding proper stacking of the active resistive switching (RS) layer for resistive random-access memory (RRAM) applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)