Heat tolerance of titanium boride and titanium nitride contacts to gallium arsenide

For contacts prepared from titanium borides by and nitrides ion-plasma sputtering onto gallium arsenide both formation mechanisms and thermal stability were investigated. We used a combination of structural, secondary-emission, optical and electrophysical methods, such as electronography, X-ray diffraction, atomic force microscopy, Auger electron spectroscopy, secondary-ion mass spectrometry, taking photoluminescence spectra and I - V curves. A physical model for contact formation was proposed. According to it, BxGa₁₋xAs (GaNxAs₁₋x) solid solutions are formed at the phase interfaces when titanium borides (nitrides) are deposited. The defects are produced in the semiconductor near-surface regions during heterostructure formation and further heat treatment. The correlation between the physico-chemical interactions at contact interfaces and the contact electrophysical parameters occurs through these defects. The objects of our investigation demonstrated high thermal stability. This was due to their two-layer structure formed by components having well-pronounced antidiffusion properties. As a result, the interdiffusion processes at the phase interfaces are drastically weakened

High mobility annealing of Transparent Conductive Oxides

To improve electrical properties a high temperature annealing treatment was applied to several transparent conductive oxides TCO , namely tin doped indium oxide ITO , Ga or Al doped ZnO ZnO Al Ga , ion beam assisted deposited IBAD ZnO Ga and Ga doped zinc magnesium oxide ZnMgO Ga . All these films were grown by magnetron sputtering. During the annealing process all TCO films were capped with 50 nm of amorphous silicon in order to protect the films from environmental impact. Increase in mobility up to 72 cm2 Vs and low resistivity of 1.6 10 amp; 8722;4 amp; 937;cm was achieved for ZnO Al after annealing at 650 C for 24 h. Independent of the deposition conditions and doping or alloying material almost all ZnO based films show a consistent improvement in mobility. Also for ITO films a decrease in resistivity with partially improved mobility was found after annealing. However, not all ITO films show consistent improvement, but carrier density above 1021 cm amp; 8722;3 while ZnO films show no clear trend for carrier density but a remarkable increase in mobility. Thus we propose the healing of defects and the activation of donors to be most significant effects for ZnO and ITO films, respectivel