Muhammad Fakhar Zia

Checkerboard Nanoplasmonic Gold Structure for Long-Wave Infrared Absorption Enhancement

A localized nanoplasmonic induced absorption enhancement in silicon nitride (Si3N4) dielectric material using a nanoscale novel checkerboard gold (Au) structure is demonstrated. The checkerboard structure is fabricated on a Si3N4 layer using electron-beam lithography and sputter deposition techniques. The plasmonic electric field and optical absorption enhancement are measured using scanning near-field optical microscopy. Finite-difference time-domain simulations are utilized to characterize the absorption spectral response enhancement together with its dependence on incidence angle and polarization. The checkerboard shows a broadband average spectral absorption enhancement of 63.2% over the wavelength range 8-12 μm with a maximum enhancement of 107% at 8 μm and a minimum enhancement of 24.8% at 12 μm. The degradation of enhanced absorption with incidence angle variation (00-60ο) is less than 1.6% at 10.6-μm wavelength. The checkerboard device shows polarization-independent absorption enhancement with incidence angles.

Thermal annealing induced multiple phase in V/V2O5 alternating multilayer structure

In this paper, we report on microstructural, optical and electrical properties of alternating multilayer of vanadium pentoxide (V2O5), 25 nm, and vanadium (V), 5 nm, thin films deposited at room temperature by radio frequency (RF) and DC magnetron sputtering, respectively. Raman and photoluminescence (PL) spectroscopy have been employed to investigate the effects of thermal annealing for 20, 30 and 40 min at 400∘C in Nitrogen (N2) atmosphere on the multiple phase formation and its impact on the film resistance and temperature coefficient of resistance (TCR). We demonstrate that the oxygen free annealing environment allows the formation of multiple phases including V2O5, V6O13 and VO2 through oxygen diffusion and consequent deficiency in V2O5 layer.

Fabrication and design of vanadium oxide microbolometer

Vanadium oxide (VxOy) multilayer sandwich structures previously studied by our group were found to yield a sensitive thermometer thin film material suitable for microbolometer applications. In this work, we aim to estimate the performance of a proposed air-bridge microbolometer configuration based on VxOy multilayer sandwich structure thermometer thin films. For this purpose, a microbolometer was fabricated on silicon (Si) substrate covered with a silicon nitride (Si3N4) insulating layer using VxOy thermometer thin film material. The fabricated microbolometer was patterned using electron-beam lithography and liftoff techniques and it was characterized in terms of its voltage repsonsivity (Rv), signal to noise ratio (SNR), noise equivalent power (NEP) and detectivity D*. A model was then developed by the aid of numerical optical/thermal simulations and experimentally measured parameters to estimate the performance of the microbolometer when fabricated in an air-bridge configuration. The estimated D* was fo...

Vanadium sesquioxide (V2O3)-based semiconducting temperature sensitive resistors for uncooled microbolometers

This paper reports on a semiconducting resistor material based on vanadium sesquioxide (V2O3) with electrical resistivity and temperature coefficient of resistance (TCR) appropriate for microbolometer applications. In this work, V2O3-based semiconducting resistor material was synthesized and electrically characterized. The developed material was prepared by annealing, in O2 and N2 atmospheres, a cascaded multilayer structure composed of V2O3 (10 nm) and V (5 nm) room temperature sputter coated thin films. The developed 55 nm thin film microbolometer resistor material possessed high temperature sensitivity from 20∘C to 45∘C with a TCR of −3.68%/∘C and room temperature resistivity of 0.57 Ω ⋅cm for O2 annealed samples and a TCR of −3.72%/∘C and room temperature resistivity of 0.72 Ω ⋅cm for N2 annealed samples. The surface morphologies of the synthesized thin films were studied using atomic force microscopy showing no significant post-growth annealing effect on the smoothness of the samples surfaces.