M. Alduraibi

Diamond heat sinking of terahertz antennas for continuous-wave photomixing

The generation of cw Terahertz radiation from photomixing in low-temperature grown GaAs is limited by the thermal load for single emitters. We propose a new heat sinking scheme based on high thermal conductivity, transparent crystalline heat spreaders as diamond in direct contact with the active zone. A first working device based on recessed electrodes is demonstrated and has a significant power dissipation capability of more than 0.75 W (average). The electrical and terahertz characteristics are analyzed.

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.

Comparison of V 2 O 5 Microbolometer Optical Performance Using NiCr and Ti Thin-Films

The optical performance characteristics of vanadium-oxide microbolometer with on-top nichrome (NiCr) thin-film metal absorber layer are evaluated using numerical simulations. A thin-film NiCr metal is sputter deposited and its optical parameters are experimentally characterized over the long-wave infrared (LWIR) range 8-

Fabrication and design of vanadium oxide microbolometer

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

m. The optical performance of microbolometer with NiCr has been compared with titanium (Ti) and without any metal thin-film. The comparison indicates that the optical absorption response of NiCr device is nearly flat and has a broadband enhancement over the LWIR range. In addition, it shows large insensitivity to variations in air-gap and metal thin-film thickness, which permits for a large fabrication tolerance. In addition, the optimized air-gap devices show that the NiCr-based device has the smallest air-gap thickness, which can lead to short leg-length and mechanically robust device.

Optical and electrical properties of stacked binary InAs-GaAs quantum dot structures prepared under Surfactant-mediated growth conditions

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...

Driveless gyroscope response of a quartz piezoelectric vibratory tuning fork

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.

Manifold sensitivity improvement of hydrocarbon odour sensors

The structural, optical and electrical properties of a 10-layer InAs/GaAs quantum dots (QDs) system having InAs layers (2.9ML) grown under surfactant growth conditions, using only an impinging In beam, were investigated. This growth mode still resulted in the formation of quantum dots, but with dot sizes smaller and sample quality better than those for normal growth (NG) of ~3ML InAs-GaAs QD structures. Room temperature photoluminescence measurements showed PL emission from this sample at 1200-1300 nm, i.e. reaching the telecom O-band. At low substrate growth temperatures (LT), 250?C, and under the same Arsenic free growth condition an InAs/GaAs superlattice structure without the formation of QD was successfully grown with up to 2.9MLs of InAs, which was not achievable under NG conditions. Both samples showed a noticeable photocurrent when illuminated with 1.2 ? 1.3 ?m lasers. Thus they can be used as photoconductive materials that can be excited with wavelength longer than that used for the well-known LT-GaAs ultrafast material and close to the telecom wavelengths of 1.3 ?m for Terahertz imaging or other optoelectronic applications.

Temperature coefficient of resistance and thermal conductivity of Vanadium oxide ‘Big Mac’ sandwich structure

In this paper, we report on the observation of a gyroscope response in the absence of drive oscillator circuitry in a single ended quartz piezoelectric tuning fork. The tuning fork gyroscope was fabricated by conventional photolithography and wet etching techniques. The tuning fork length is 4 mm and the stem length is 2 mm; the tuning fork width and thickness are 0.4 mm and 0.35 mm, respectively. The measured gyroscope sensitivity and signal to noise ratio were 0.22 mV/°/s and 40, respectively, at a rotational rate of 60 °/s.

Synthesis and electrical characterisation of vanadium oxide thin film thermometer for microbolometer applications

We show that the sensitivity of swelling-based gold core-shell nanoparticle (Au CSNP) chemiresistors for vapour sensing can be enhanced considerably by cooling such sensors with respect to ambient temperature. We explain this by the increased swelling of the ligand shell at lower temperature due to the reduced volatility of the analyte. This interpretation is supported quantitatively by measurement and analysis of sensitivity at different temperatures, and to different vapours. Sensitivity to a particular vapour scales with temperature in the same way as that vapours saturated vapour pressure. That allows quantitative prediction of sensitivity enhancement for vapours not yet tested, as long as their enthalpy of vaporisation is known. We believe our conclusions apply to all sensors that work by swelling in analyte vapour.