BITS Faculty Publications
Permanent URI for this communityhttp://localhost:4000/handle/123456789/1867
Browse
7 results
Search Results
Item Comprehensive modeling of gas sensor based on Si3N4-passivated AlGaN/GaN Schottky diode(IEEE, 2014) Kumar, RahulA physics-based analytical modeling for the gas sensor application of AlGaN/GaN heterostructure Schottky diode has been investigated for high linearity and sensitivity of the device. The heterointerface and surface properties are exploited here. The dependency of 2DEG on the surface charge, which is dependent on the Si 3 N 4 passivation layer, is mainly utilized to model the device. The simulation of Schottky diode has been performed in the TCAD tool and I-V curves are generated. From the I-V curves, 54% response has been recorded in presence of 500 ppm gas and at biasing voltage of 0.95 Volts.Item Simplified gas sensor model based on AlGaN/GaN heterostructure Schottky diode(AIP, 2015-08) Kumar, RahulPhysics based modeling of AlGaN/GaN heterostructure Schottky diode gas sensor has been investigated for high sensitivity and linearity of the device. Here the surface and heterointerface properties are greatly exploited. The dependence of two dimensional electron gas (2DEG) upon the surface charges is mainly utilized. The simulation of Schottky diode has been done in Technology Computer Aided Design (TCAD) tool and I-V curves are generated, from the I-V curves 76% response has been recorded in presence of 500 ppm gas at a biasing voltage of 0.95 VoltItem Enhancement of two dimensional electron gas concentrations due to Si3N4 passivation on Al0.3Ga0.7N/GaN heterostructure: strain and interface capacitance analysis(AIP, 2015) Kumar, RahulEnhancement of two dimensional electron gas (2DEG) concentrations at Al0.3Ga0.7N/GaN hetero interface after a-Si3N4 (SiN) passivation has been investigated from non-destructive High Resolution X-ray Diffraction (HRXRD) analysis, depletion depth and capacitance-voltage (C-V) profile measurement. The crystalline quality and strained in-plane lattice parameters of Al0.3Ga0.7N and GaN were evaluated from double axis (002) symmetric (ω-2θ) diffraction scan and double axis (105) asymmetric reciprocal space mapping (DA RSM) which revealed that the tensile strain of the Al0.3Ga0.7N layer increased by 15.6% after SiN passivation. In accordance with the predictions from theoretical solution of Schrödinger-Poisson’s equations, both electrochemical capacitance voltage (ECV) depletion depth profile and C-V characteristics analyses were performed which implied effective 9.5% increase in 2DEG carrier density after passivation. The enhancement of polarization charges results from increased tensile strain in the Al0.3Ga0.7N layer and also due to the decreased surface states at the interface of SiN/Al0.3Ga0.7N layer, effectively improving the carrier confinement at the interfaceItem Fowler–Nordheim Tunnelling Contribution in AlGaN/GaN on Si (111) Schottky Current(Taylor & Francis, 2016) Kumar, RahulAlGaN/GaN heterojunction with Schottky metal contact can be modelled with two back-to-back diodes. The forward-biased diode between metal and AlGaN barrier acts at the onset of current with positive bias. Fowler– Nordheim tunnelling is mainly responsible for the electron transport at the low positive bias level. Downward energy band bending of AlGaN barrier with further positive voltage reduces the tunnelling probability due to lowering of the barrier height of the first diode, causing a dramatic change in the current.Item Thermodynamic analysis of acetone sensing in Pd/AlGaN/GaN heterostructure Schottky diodes at low temperatures(Elsevier, 2016-03) Kumar, RahulAn AlGaN/GaN heterostructure based metal–semiconductor–metal symmetrically bi-directional Schottky diode sensor structure has been employed to investigate acetone sensing and to analyze thermodynamics of acetone adsorption at low temperatures. The AlGaN/GaN heterostructure has been grown by plasma-assisted molecular beam epitaxy on Si (111). Schottky diode parameters at different temperatures and acetone concentrations have been extracted from I–V characteristics. Sensitivity and change in Schottky barrier height have been studied. Optimum operating temperature has been established. Coverage of acetone adsorption sites at the AlGaN surface and the effective equilibrium rate constant of acetone adsorption have been explored to determine the endothermic nature of acetone adsorption enthalpy.Item Reverse bias leakage current mechanism of AlGaN/InGaN/GaN heterostructure(Springer, 2016-03) Kumar, RahulThe reverse bias leakage current mechanism of AlGaN/InGaN/GaN heterostructure is investigated by current-voltage measurement in temperature range from 298 K to 423 K. The Higher electric field across the AlGaN barrier layer of AlGaN/InGaN/GaN double heterostructure due to higher polarization charge is found to be responsible for strong Fowler-Nordheim (FN) tunnelling in the electric field higher than 3.66 MV/cm. For electric field less than 3.56 MV/cm, the reverse bias leakage current is also found to follow the trap assisted Frenkel-Poole (FP) emission in low negative bias region. Analysis of reverse FP emission yielded the barrier height of trap energy level of 0.34 eV with respect to Fermi level.Item Highly Sensitive Acetone Sensor Based on Pd/AlGaN/GaN Resistive Device Grown by Plasma-Assisted Molecular Beam Epitaxy(IEEE, 2017-11) Kumar, RahulHighly sensitive acetone sensing performance of Pd/AlGaN/GaN resistive devices in the temperature range of 100 °C-250 °C and in the detection range of 100-1000 ppm was reported. A plasma-assisted molecular beam epitaxy was used to grow the AlGaN/GaN heterostructure on Si (111) substrate. Structural characterization of the grown epilayers was performed through double-crystal X-ray diffraction whereas atomic force microscopy was used to obtain the roughness of the sensing surface. Resistive mode configuration of the sample was tested toward acetone in the detection range of 100-1000 ppm and in the temperature range of 100 °C-250 °C. The optimum temperature was found to be 150 °C with response magnitude ~95% for the acetone concentration of 1000 ppm. The sensor response time and recovery time were found to be in the range of ~18-44 s and ~25-109 s, respectively. The cross-sensitivity of the device with other interfering species such as butanone, benzene, toluene, and xylene attributed to good acetone selectivity of the devices. Acetone sensing as well as current transport of the Pd/AlGaN/GaN devices was illustrated with effect including Langmuir adsorption-desorption kinetics and Schottky barrier height between Pd/AlGaN interfaces.