Routu Santosh

The experimental and theoretical realization of 10% graphene doped ZnO/Graphene thin film alcohol sensor has been reported. The alcohol sensor has been fabricated by sol-gel method and theoretically verified by DFT-based first principle calculations. The quality of the fabricated device has been studied using SEM and UV measurements. To determine its figures-of-merit, the conductivity, transfer characteristics, and response measurements have been analyzed. In addition, the device has undergone three different exposures of alcohol concentrations such as Brandy, Whiskey, and Rum with varying exposure times.

The electronically tunable differentiator using a voltage difference transconductance amplifier (VDTA) is proposed, designed, and analyzed. The simulation was done using the Cadence Virtuoso tool of 45 nm CMOS technology with a supply voltage of ±0.9 V. The maximum power consumption of the proposed circuit is 246 [ ]W with a total harmonic distortion of 5.4%. The output can be tuned using four parameters: [ ], [ ], [ ], and [ ]. The transconductance can be varied using bias current and aspect ratio of CMOS transistors. The utilized area of VDTA layout is 1075.81 [ ]m². The parasitic impedance affects the output of post-layout simulation and causes little delay compared to schematic. The design has been experimentally verified using LM13700 integrated circuit. The results of the proposed circuit show good agreement with the experimental results and mathematical expressions. The proposed circuit can be used as a tunable PD controller, in which the voltage gain of the proposed circuit is [ ]. The design is versatile and can be used in different applications such as temperature control systems, photo voltaic cells, waveform generators, microwave communications systems, and instrumentation systems.

Context The new equations have been developed for the structural and electronic properties using the plasmon calculations for the first time for 2-D MoX₂ structures. Literature shows still an extensive study is required on the stability and optical properties of MoX2 under different hydrostatic pressures and thermal properties under different temperatures using the first principles, for electronic industrial applications. The stability is analyzed using binding energy and phonon calculations. The phase transition of metallization of MoX₂ is discussed using band structure calculations under different hydrostatic pressures. The calculated work function shows the photoemission starts from the threshold frequency of 4.189×10⁴ cm^-1, 3.184×10⁴ cm^-1, and 3.651×10⁴ cm^-1, respectively, for MoS₂, MoSe₂, and MoTe₂ materials. The optical properties such as refractive index n(0), and static dielectric permittivity ε(0) for three successive materials are calculated under different hydrostatic pressures, applicable for optoelectronic applications. The calculated theoretical and computational values agree well with each other and also agree with reported and experimental values. Some of the values are calculated for the first time. Methods The theoretical equations are derived using the molecular weight, effective valence electrons, and density of molecule of MoX₂ structures. The simulation work is performed using GGA-PBE approximation in the CASTEP simulation package with DFT+D semi-empirical dispersion correction. An ultra-soft pseudopotential representation calculates the electronic and optical properties with a finite basis set kinetic energy cut-off of 381.0 eV. Each geometry has been optimized using Broyden, Fletcher, Goldfarb, and Shanno's (BFGS) algorithm for 100 iterations with a fixed basis quality variable cell method and finite electronic minimization parameters. The phonon calculations were performed using TDFT with a kinetic energy cut of 460 eV in a norm-conserving linear response method. The interpolation with a finite dispersion quality and q-vector grid spacing is performed.

The structural, electronic, and optical properties of hydrogenated silicene have been investigated using first-principles DFT calculations. Compared to pristine silicene, hydrogenated silicene exhibits high stability, reduced anisotropy, and less birefringence. Hydrogenated silicene shows a constant refractive index in the visible region, increasing exponentially in silicene. The elastic and optical parameters such as Young’s modulus (Y), Poisson’s ratio (ν), bulk modulus (B), shear modulus (G), dielectric constant ε(0), refractive index n(0), conductivity threshold (E_th), birefringence Δn(0), and plasmon energy (ħω_p) were calculated for the first time for different hydrogen coverage on silicene, which is crucial in the applications of linear and non-linear optoelectronic devices. The estimated parameters agree well with the available experimental and reported values.

The structural, electronic, and optical properties of hydrogenated silicene have been investigated using first-principles DFT calculations. In comparison to pristine silicene, the hydrogenated silicene exhibits high stability, reduced anisotropy, and less birefringence. In the visible range, hydrogenated silicene exhibits a constant refractive index than silicene. The elastic and optical parameters: Young’s modulus (Y), poisson’s ratio (ν), bulk modulus (B), shear modulus (G), dielectric constant ε(0), refractive index n(0), conductivity threshold (E_th), birefringence Δn(0), and plasmon energy (ħω_p) were calculated for the first time for various hydrogen occupancy levels. The estimated parameters are agree well with the experimental and reported values that are available.