arXiv subjects

Padmalochan Panda

Publications and source records attributed to Padmalochan Panda.

4 recordsLinked to original sources

arXiv2025

Beyond 5 GHz excitation of a ZnO-based high-overtone bulk acoustic resonator on SiC substrate

This work reports on the fabrication and characterization of an Au/ZnO/Pt-based high-overtone bulk acoustic resonator (HBAR) on SiC substrates. We evaluate its microwave characteristics comparing with Si substrates for micro-electromechanical applications. Dielectric magnetron sputtering and an electron beam evaporator are employed to develop highly c-axis-oriented ZnO films and metal electrodes. The crystal structure and surface morphology of post-growth layers have been characterized using X-ray diffraction, atomic force microscopy, and scanning electron microscopy techniques. HBAR on SiC substrate results in multiple longitudinal bulk acoustic wave resonances up to 7 GHz, with the strongest excited resonances emerging at 5.25 GHz. The value of f.Q (Resonance frequency * Quality factor) parameter obtained using a novel Q approach method for HBAR on SiC substrate is 4.1 * 10^13 Hz, which to the best of our knowledge, is the highest among all reported values for specified ZnO-based devices.

physics.app-ph↗

arXiv2024

Glucose Sensing Using Pristine and Co-doped Hematite Fiber-Optic sensors: Experimental and DFT Analysis

Glucose monitoring plays a critical role in managing diabetes, one of the most prevalent diseases globally. The development of fast-responsive, cost-effective, and biocompatible glucose sensors is essential for improving patient care. In this study, a comparative analysis is conducted between pristine and Co-doped hematite samples, synthesized via the hydrothermal method, to evaluate their structural, morphological, and optical properties. The glucose sensing performance of both samples is assessed using a fiber-optic evanescent wave (FOEW) setup. While the sensitivity remains comparable for both pristine and Co-doped hematite, a reduction in the Limit of Detection (LoD) is observed in the Co-doped sample, suggesting enhanced interactions with glucose molecules at the surface. To gain further insights into the glucose adsorption mechanisms, Density Functional Theory (DFT) calculations are performed, revealing key details regarding charge transfer, electronic delocalization, and glucose binding on the hematite surfaces. These findings highlight the potential of Co-doped hematite for advanced glucose sensing applications, offering a valuable synergy between experimental and theoretical approaches for further exploration in biosensing technologies.

physics.med-ph↗

arXiv2018

Spectroscopic Ellipsometry investigation on anisotropic optical properties of sputtered AlN films

We report the uniaxial anisotropic optical constants of Wurtzite type AlN films deposited on Si (100) substrate using DC reactive magnetron sputtering as a function of growth temperature (Ts, 35 to 600 C). Evolution of optical properties with Ts is investigated by Spectroscopic Ellipsometry (SE) technique. Thickness and roughness of these films are determined from the regression analysis of SE data, which are corroborated using TEM and AFM technique. Highly a-axis oriented AlN film grown at 400 C, exhibits high n and low k at 210 nm (deep-UV region) with a small birefringence and dichroism near to band edge, which can be used in isotropic deep UV optoelectronic device applications. All these AlN films exhibit transparent nature from near-infrared (NIR) to 354 nm, where optical band gap energies vary between 5.7 to 6.1 eV.

cond-mat.mtrl-sci↗

arXiv2016

Reduction of residual stress in AlN thin Films synthesized by magnetron sputtering technique

We report the reduction in residual stress of AlN thin films and also the crystal structure, surface morphology and nanomechanical properties of magnetron sputtered as a function of substrate temperature (Ts, 35 - 600 ?C). The residual stress of these films was calculated by sin2 technique and found that they are varying from tensile to compression with temperature (Ts). Evolution of crystalline growth of AlN films was studied by GIXRD and transmission electron microscopy (TEM) and a preferred a-axis orientation was observed at 400 ?C. The cross-sectional TEM micrograph and selected area electron difraction (SAED) of this film exhibited a high degree of orientation as well as a columnar structure. Hardness (H) measured by Nanoindentation technique on these films ranged between 12.8 - 19 GPa.

cond-mat.mtrl-sci↗