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At least 73 records · Page 4

Dilute antimonide nitride for long wavelength infrared photodetection

InSb{sub 1−x}N{sub x} materials were fabricated by direct nitrogen implantation into InSb wafer and they are characterized by X-ray diffraction, Hall measurement, X-ray photoelectron spectroscopy. In-N bonds are clearly demonstrated and other forms of nitrogen, such as antisites (N{sub In}), interstitial N{sub 2}, also exist in the grown films. The ratio to the total nitrogen bonds formed in the materials varies with preparation conditions. The optical bandgap data confirmed bandgap narrowing due to the incorporation of nitrogen. Photoconductive and photovoltaic photodetectors are fabricated and the cut-off frequencies of up to 11.5 μm are demonstrated.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Structural, morphological and Raman studies of pulse electrosynthesised indium antimonide thin films

InSb films deposited on fluorine doped tin oxide (FTO) substrates by a pulse elctrodeposition technique. The deposition was carried out at an applied potential −1.3V versus Ag/AgCl electrode. Structural, morphological and optical studies were performed on the electrodeposited InSb. X-ray diffraction (XRD) studies show that the deposited InSb films are polycrystalline in nature having the zinc blend structure. The crystallite size (D), dislocation density (δ) and strain (ε) were calculated using XRD results. The EDAX analysis shows that chemical composition of In{sup 3+} and Sb{sup 3+} ions is close to the required stoichiometry. The surface morphology of the deposited films was examined using scanning electron microscopy (SEM). SEM studies reveal that the surface of the films is uniformly covered with submicron sized spherical particles. However, the crystallite size determined by the Scherrer method shows a size close to 30 nm. Surface morphology studies of the InSb films were also performed using atomic force microscopy (AFM). The average surface roughness as measured by AFM is around 40 nm. Hot probe studies show that all the electrodeposited thin films have n type conductivity and the thickness of the films is calculated using electrochemical formula.

36 MATERIALS SCIENCE↗

Thermal emittance and lifetime of alkali-antimonide photocathodes grown on GaAs and molybdenum substrates evaluated in a –300 kV dc photogun

In this work, Cs x K y Sb photocathodes grown on GaAs and molybdenum substrates were evaluated using a –300 kV dc high voltage photogun and diagnostic beam line. Photocathodes grown on GaAs substrates, with varying antimony layer thickness (estimated range from <20 nm to >1 um), yielded similar thermal emittance per rms laser spot size values (~0.4 mmmrad=mm) but very different operating lifetime. Similar thermal emittance was obtained for a photocathode grown on a molybdenum substrate but with markedly improved lifetime. For this photocathode, no decay in quantum efficiency was measured at 4.5 mA average current and with peak current 0.55 A at the photocathode.

43 PARTICLE ACCELERATORS↗