Department of Electrical and Electronics Engineering
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Item CsGeI3 perovskite-based solar cells for higher efficiency and stability: an experimental investigation(IEEE, 2025-05) Mourya, Satyendra KumarAmong the recent developments in photovoltaic technologies, perovskite solar cells (PSCs) have drawn significant attention, owing to their exceptional power conversion efficiency (PCE), cost-effectiveness, and better optoelectronic characteristics. However, the stability and presence of lead (toxicity) in PSCs remains a major challenge to their commercialization. In this study, we experimentally investigated all-inorganic, lead-free CsGeI3-based PSCs in an n-i-p configuration. The CsGeI3 films were synthesized using a one-step spin-coating technique and their crystallographic characteristics were analyzed. Furthermore, we fabricated and tested different device architectures incorporating CsGeI3 as the absorber layer with various electron transport layers (ETLs), including TiO2, ZnO, and graphene oxide (GO), while employing MoS2 as the hole transport layer. The resulting device structure was Fluorine doped Tin oxide (FTO)/(TiO2/ZnO/GO)/CsGeI3/MoS2/Ni). All fabricated devices demonstrated excellent performance, with the TiO2-based ETL device achieving the highest PCE of 10.79%. In addition, incorporating reduced graphene oxide (rGO) as an interface layer on top of the absorber layer further enhanced photovoltaic performance by approximately 3% across all configurations (achieving outstanding efficiency of 13.57%). The hydrophobic nature and high conductivity of rGO suggest its potential as a promising strategy for improving the stability and efficiency of lead-free PSCs in future applications.Item Spin-orbit torque MRAM performance with different materials(IOP, 2025-08) Mourya, Satyendra Kumarspin–orbit torque (SOT) technology has emerged as a promising approach for developing advanced magnetic devices with superior performance metrics. The SOT enables efficient control of magnetic states through the generation of spin currents via spin–orbit interaction. The precise control in magnetization switching with low power consumption in SOT based devices offers advancements in memory and logic applications. This paper presents a comparative study of the various parameters related to SOT performance across a range of materials, including Bi2Se3, Pt, Ta, W, WTe2, MoTe2, and IrMN. By analyzing key material properties such as spin-Hall conductivity (SHC), resistivity, damping constant, and spin-Hall angle (SHA). We evaluate how these factors influence the efficacy of SOT applications. The critical current density and material properties are key parameters for magnetization switching. Further, we explore the retention time and temperature stability for each material. Our findings aim to identify optimal materials for SOT-based devices and provide a framework for selecting materials based on specific performance criteria. This comparative analysis contributes to the progression of SOT technology and supports the progress of next-generation spintronic devices.Item High-performance self-biased Cu/SiC/Si photo-sensor with swift response for NIR/Vis photodetection(Elsevier, 2024-08) Mourya, Satyendra KumarSilicon Carbide (SiC) shows great potential for use in high temperatures and harsh environments due to its promising physical properties. This report introduces a novel double depletion functional heterointerface comprising a multilayer structure of Cu/SiC/Si. High-quality nanocrystalline SiC thin films are fabricated on p-type Silicon (Si) by RF magnetron sputtering at a relatively low temperature of 900 °C as compared to conventional methods. A multilayer photo-sensor device, comprising Cu/SiC/Si layers, is fabricated through the thermal evaporation of Cu metal using a shadow mask. The device exhibits good photo-response at both 750 nm and 440 nm wavelengths. Both the junctions Cu/SiC and SiC/Si play role in generating electron-hole pairs along the depth of the device. The device exhibits a very high responsivity of 1.26 A/W and a rapid response of 94/137 ms at a wavelength of 750 nm at self-bias conditions. It also demonstrates a high responsivity of 0.46 A/W and a very fast response time of 66.8/66.4 ms for 440 nm wavelength. Owing to its impressive performance, this device distinguishes itself as a superior choice among state-of-the-art SiC-based photodetectors. Its significance lies in the robust stability of the SiC/Si junction in high-temperature settings, surpassing low bandgap materials for NIR/vis photodetectors.Item Study of Quantum Dot Solar Cell Including CdTe Quantum Dots Embedded in Al0.3 Ga0.7 As/GaAs Quantum Wells(IEEE, 2024) Mourya, Satyendra KumarIntermediate Band Solar Cells were proposed in 1997 as an alternative to tandem solar cells to achieve high efficiency in a photovoltaic device. It has a proposed theoretical limit of 63.2%, much higher than the 33% of a single-junction solar cell. In this study, we explore the photovoltaic performance of CdTe Quantum Dots embedded in Al0.3Ga0.7As/GaAs Quantum Wells for the first time using SCAPS-1D software. This arrangement leads to the formation of intermediate energy levels due to Quantum Confinement, which has been exploited to form a Hole Injection Layer and increase Quantum Efficiency. Further, a detailed study of the device’s band diagram in both illuminated and illuminated cases is provided, offering crucial insights into its performance and working. The best-optimized device yielded a maximum power conversion efficiency of 31.8%, Quantum Efficiency (QE) of 80% over the visible range, open-circuit voltage VOC of 1.36 and fill factor (F= r) ranging between 77%−85%.Item Analysis of temperature sensitive electrical performance of sputter grown Ni and Ni–Cr Schottky contacts on 4 H-SiC(Springer, 2024-11) Singh, Dheerendra; Mourya, Satyendra Kumar; Bhatt, Upendra MohanThis paper studies the temperature-dependent electrical transport properties of nickel (Ni) and nickel–chromium (Ni–Cr) sputtered on n-type 4 H-SiC substrate. Barrier inhomogeneities have been found to affect the electrical parameter of the Schottky barrier diode (SBD) from 323 to 423 K temperature range, We have done current–voltage characterization of Ni and Ni–Cr Schottky junctions. The barrier height , reverse saturation current , ideality factor and series resistance were obtained from I–V characteristics of Ni and Ni–Cr and these parameters are observed to be highly dependent on temperature. It has been observed that Ni–Cr contact has exhibited better electrical characteristics as well as thermal sensitivity as compared to Ni. This may be attributed to the smaller number of barrier inhomogeneities at the Ni–Cr/4 H-SiC interface. In the temperature range from 323 to 423 K, Ni and Ni–Cr-based Schottky contacts, Following observation has been noticed (a). Schottky barrier height (SBH) increased from 1.24 to 1.37 eV and 1.15 to 1.45 eV, (b). Ideality factors reduced from 3.76 to 2.61 and 3.20 to 2.53, (c). Series resistance decreased from 10.22 to 3.37 and 2.45 to 1.16 , and (d). Reverse leakage current to A and to A respectively. The V–T curves for both SBDs are investigated (for the same temperature range) to calculate their thermal sensitivity at and A, respectively. The V–T curves with linear behavior are used to calculate the thermal sensitivity coefficient , which was found to be 7.11 to 7.93 mV/K for the Ni–Cr SBD, and 7.1 to 20.01 mV/K for the Ni/4 H-SiC contacts. The sensitivity-current characteristics for the Ni/4 H-SiC SBD were found to be a non-linear comparison with Ni–Cr/4 H-SiC SBD, which may be attributed to the presence of a highly resistive and non-uniform coating of Ni at the interface.Item Submonolayer InAs Quantum Dot Based Solar Cell: A New Approach Towards Intermediate Band Solar Cell(Bentham Science, 2023) Mourya, Satyendra Kumar; Kumar, RahulThis chapter summarizes the progress of InAs submonolayer (SML) quantum dot (QD) based intermediate band solar cell (IBSC). A brief background of intermediate band solar cells (IBSC) will be presented. Different IBSC prototypes will be discussed. The importance of quantum dots (QDs) for IBSC prototyping will be illustrated. An alternative of the most extensively used Stranski-Krastanow (SK)-QDs named SML QDs will be introduced. The fabrication of SML-QD-based IBSC will be discussed from the material point of view. We will also discuss the physics behind the improved performance of these SCs. Important research in this field will be reviewed. Finally, the future direction will be suggested to further improve the performance.Item Reduction of off-state drain current in AlN/β-Ga₂O₃ HEMT by trap state engineering(Elsevier, 2024-05) Mourya, Satyendra Kumar; Kumar, RahulIn this work, we report various strategies to reduce the off-state drain leakage current () in AlN/ high electron mobility transistor (HEMT) by 2D device simulation. We have investigated the effect of access region, channel doping concentration, barrier layer thickness, and trap state engineering on . The formation of a parallel channel deep into the substrate has been found to be responsible for large . All other strategies except trap state engineering have an incremental effect on . However, the device’s was reduced by around 12 orders of magnitude by trap-state engineering. Simultaneously, the on-state performance was unaffected, resulting in an elevated / current ratio of (). A steep subthreshold slope of 0.267 (V/dec) was also obtained. Further, we have investigated the impact of both donor- and acceptor-type traps on subthreshold characteristics. These promising results highlight the potential of AlN/ HEMT as a switch and for future high-power nanoelectronics applications.Item Highly Sensitive and Selective H2 Gas Sensor Based on Pd-Pt Decorated Nanostructured Silicon Carbide Thin Films for Extreme Environment Application(World Academy of Science, Engineering and Technology, 2007-01) Mourya, Satyendra KumarPresent work describes the fabrication and sensing characteristics of the Pd-Pt decorated nanostructured silicon carbide (SiC) thin films on anodized porous silicon (PSi) substrate by RF magnetron sputtering. The gas sensing performance of Pd-Pt/SiC/PSi sensing electrode towards H2 gas under low (10–400 ppm) detection limit and high operating temperature regime (25–600 °C) were studied in detail. The chemiresistive sensor exhibited high selectivity, good sensing response, fast response/recovery time with excellent stability towards H2 at high temperature. The selectivity measurement of the sensing electrode was done towards different oxidizing and reducing gases and proposed sensing mechanism discussed in detail. Therefore, the investigated Pd-Pt/SiC/PSi structure may be a highly sensitive and selective hydrogen gas sensing electrode for deployment in extreme environment applicationsItem Enhanced Optical Absorbance Of Hydrophobic Ti Thin Film: Role Of Surface Roughness(IJMS, 2016) Mourya, Satyendra KumarIn the present work, structural, morphological, optical and wettability properties of DC magnetron sputtered titanium (Ti) thin films have been investigated. The nanostructured Ti thin films were deposited on glass and silicon substrates at various deposition angles, θD = 0°, 30°, 45° and 60°. HCP structure of Ti thin films with preferred peak orientations (100) and (002) were revealed from XRD. It was observed that as the deposition angle increases, film thickness (~260 - 100 nm) as well as average crystallite size (~27 - 11 nm) of Ti thin films decrease. Significant changes in topography of the films, with change in deposition angle, have been observed. The optical and wettability results suggested that transmission, reflection, absorption and water contact angle of Ti thin films are strongly influenced by deposition angle due to change in its surface roughness. The large near infrared (NIR) absorbance (~ 66 - 75%) was found for the sample deposited at θD = 30°, which exhibited hydrophobic (~ 94.6°) nature with high surface roughness (~ 28 nm).Item Determination of optical constants including surface characteristics of optically thick nanostructured Ti films: analyzed by spectroscopic ellipsometry(OSA Open Access, 2016) Mourya, Satyendra KumarIn the present work, optically thick nanostructured titanium (Ti) films of thickness ranging from ∼100 to 900 nm were deposited on a glass substrate by DC magnetron sputtering at room temperature. Microstructural and surface properties of the samples were studied by x-ray diffraction and x-ray photoelectron spectroscopy (XPS). The morphological results revealed a systematic normal grain growth mechanism with increasing thickness analyzed by a scanning electron microscope. The influence of thickness on film surface roughness has been investigated by atomic force microscopy (AFM). The optical dispersion behavior was examined by spectroscopic ellipsometry (SE) over the long wavelength range of 246–1688 nm. The experimentally observed SE parameters were theoretically fitted with Drude–Lorentz and Bruggeman effective medium approximation theory. The surface properties of the Ti film measured by XPS and AFM were further accounted for in the optical model to determine optical constants (𝑛 and 𝑘) and the obtained results are expected to be the best available for bulk Ti metal.
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