Department of Electrical and Electronics Engineering

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Has files: NoSubject: search.filters.subject.Silicon carbide (SiC) thin films

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    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 Kumar
    Present 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 applications
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    The Role of the Substrate on Photophysical Properties of Highly Ordered 15R-SiC Thin Films
    (Springer, 2018-06) Mourya, Satyendra Kumar
    We report on the structural optimization and photophysical properties of in situ RF-sputtered single crystalline 15R-SiC thin films deposited on various substrates (ZrO2, MgO, SiC, and Si). The role of the substrates on the structural, electronic, and photodynamic behavior of the grown films have been demonstrated using x-ray diffraction, photoluminescence (PL) and time-resolved photoluminescence spectroscopy. The appropriate bonding order and the presence of native oxide on the surface of the grown samples are confirmed by x-ray photoelectron spectroscopy measurement. A deep-blue PL emission has been observed corresponding to the Si-centered defects occurring in the native oxide. Deconvolution of the PL spectra manifested two decay mechanisms corresponding to the radiative recombination. The PL intensity and carrier lifetime were found to be substrate- dependent which may be ascribed to the variation in the trap-density of the films grown on different substrates.
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    Structural and optical characteristics of in-situ sputtered highly oriented 15R-SiC thin films on different substrates
    (AIP, 2018-01) Mourya, Satyendra Kumar
    In this work, we have reported the in-situ fabrication of nanocrystalline rhombohedral silicon carbide (15R-SiC) thin films by RF-magnetron sputtering at 800 °C substrate temperature. The structural and optical properties were investigated for the films grown on four different substrates (ZrO2, MgO, SiC, and Si). The contact angle measurement was performed on all the substrates to investigate the role of interfacial surface energy in nucleation and growth of the films. The XRD measurement revealed the growth of (1 0 10) orientation for all the samples and demonstrated better crystallinity on Si substrate, which was further corroborated by the TEM results. The Raman spectroscopy confirmed the growth of rhombohedral phase with 15R polytype. Surface characteristics of the films have been investigated by energy dispersive x-ray spectroscopy, FTIR, and atomic force microscope (AFM) to account for chemical composition, bonding, and root mean square surface roughness (δrms). The optical dispersion behavior of 15R-SiC thin films was examined by variable angle spectroscopic ellipsometry in the wide spectral range (246–1688 nm), including the surface characteristics in the optical model. The non-linear optical parameters (χ3 and n2) of the samples have been calculated by the Tichy and Ticha relation using a single effective oscillator model of Wemple and Didomenico. Additionally, our optical results provided an alternative way to measure the ratio of carrier concentration to the effective mass (N/m*). These investigated optical parameters allow one to design and fabricate optoelectronic, photonic, and telecommunication devices for deployment in extreme environment
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    Ellipsometric Investigation of Room Temperature Grown Highly-Oriented Anatase TiO2 Thin Films
    (Springer, 2018-12) Mourya, Satyendra Kumar
    In this article, we have reported the structural optimization and optical properties of anatase titanium dioxide (TiO2) thin films grown by direct current magnetron sputtering on a glass substrate at room temperature (RT). The x-ray diffraction measurement revealed anatase phase of TiO2 with preferred orientation (101). The morphological, compositional and topographical properties of the samples are explored by scanning electron microscopy, x-ray photoelectron spectroscopy and atomic force microscopy, respectively. The optical properties such as refractive index n, extinction coefficient k and optical bandgap Eg are determined in the broad wavelength range of 246–1688 nm using variable angle spectroscopic ellipsometry accounting for the surface properties in the optical stack model. Moreover, the nonlinear refractive index n2 and the third-order nonlinear optical susceptibility χ(3) are determined using the Tichy–Ticha relation and Wemple–Didomenico (WDD) parameters. The ratio of the carrier concentration to the effective mass N/m* has also been determined. The current research on the optical and dispersion energy parameters of RT grown anatase TiO2 thin films is expected to have a significant impact on advanced flexible optical, optoelectronic, and photonic applications.
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    Development of Pd-Pt functionalized high performance H2 gas sensor based on silicon carbide coated porous silicon for extreme environment applications
    (Elsevier, 2019-03) Mourya, Satyendra Kumar
    Present work demonstrates the hydrogen gas (H2) sensing characteristics of palladium-platinum (Pd-Pt) functionalized silicon carbide (SiC) thin film grown on porous silicon (PSi) substrate for high temperature applications. Nano-crystalline SiC thin film was deposited by RF magnetron sputtering on anodized PSi substrate. The loading of discrete ultra-thin Pd-Pt bimetallic catalytic layer was carefully controlled by varying the sputtering parameters. The proposed device architecture (Pd-Pt/SiC/PSi) revealed significant advantages, such as stable high sensing response, large tunable detection range (5–500 ppm), fast response/recovery time, excellent reproducibility, high selectivity, wide operating temperature regime (25–500 °C) and good durability. The observed high response may be ascribed to the combined effect of enhanced catalytic activity of bimetallic Pd-Pt layer and increased surface area of the proposed sensor.
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    Coexistence of Space Charge Limited and Variable Range Hopping Conduction Mechanism in Sputter-Deposited Au/SiC Metal–Semiconductor–Metal Device
    (IEEE, 2023-02) Mourya, Satyendra Kumar
    Despite being the cornerstone of high-temperature and high-power applications, the fabrication of silicon carbide (SiC) thin films has been a major challenge among research activities related to wide bandgap semiconductors. As almost all the reported SiC thin films produced by RF sputtering are amorphous, the growth of crystalline thin film on p-type silicon substrate at high temperature (>900 °C) is presented in this work. A metal–semiconductor–metal (MSM) device is fabricated with gold (Au) electrodes by sputtering. A unique behavior of current–voltage ( I – V ) characteristics is found in different voltage regimes. The thermionic emission model fails to explain the observed I – V characteristics. To understand the current transport mechanism in detail, I – V characteristics are carried out in the temperature range 250–380 K and divided into two voltage regimes, below and above 1 V. Below 1 V, variable range hopping mechanism (VRH) is found to be dominant and above 1 V, and ohmic conduction followed by space charge limited conduction (SCLC) is held accountable for the current transport mechanism. The analysis of both mechanisms indicates the presence of disorder states and gives valuable information about trap centers. The C – V characteristics further suggest the presence of interface states and deep traps. The advantageous implementation of this information will help to design optoelectronic, magnetic, and efficient energy storage devices to extract the maximum performance.