- Cocks, F.H. and Jones, P.L. and Dimmey, L.J., The optical band gap of hydrogenated amorphous-boron thin films: the effect of thermal treatment,
Appl. Phys. Lett. (USA), vol. 36 no. 12
pp. 970 - 2 [1.91386] .
(last updated on 2007/04/10)
Hydrogenated amorphous-boron thin films produced by glow-discharge decomposition of a gas mixture of 3.1 vol.% diborane and 96.9 vol.% hydrogen have been heat treated at 360 and 400°C. The resulting absorption coefficients and optical band gaps have been measured as a function of heat-treatment time and temperature. Both the absorption coefficients and the optical band gaps of these films can be drastically changed by such treatments. Thermal treatment at 400°C for 200 h results in systematic decrease in the optical band gap from 2.19 to 0.90 eV. From quantitative hydrogen analyses it is shown that hydrogen evolution during heating plays a strong role in reducing the apparent optical band gap. These results indicate that it might be possible to optimize theoretical amorphous-boron thin films through the tailoring of the optical band gap by such thermal treatment
boron;energy gap;heat treatment;hydrogen;optical constants;plasma deposited coatings;