No abstract

We study the relationship between the optical gap and the optical-absorption tail breadth for the case of amorphous gallium arsenide (a-GaAs). In particular, we analyze the optical-absorption spectra corresponding to some recently prepared a-GaAs samples. The optical gap and the optical-absorption tail breadth corresponding to each sample is determined. Plotting the optical gap as a function of the corresponding optical-absorption tail breadth, we note that a trend, similar to that found for the cases of the hydrogenated amorphous silicon and hydrogenated amorphous germanium, is also found for the case of a-GaAs. The impact of alloying on the optical-absorption spectrum associated with a-GaAs is also briefly examined.

No abstract

In this work the electrical properties of nitrogen-doped hydrogenated amorphous germanium films ͑a-Ge:H͒ using ammonia ͑NH 3 ͒ as a gaseous doping source are reported. The results are compared with those of N-doped a-Ge:H films using N 2 as a source gas. The doping mechanisms appear to be similar in both cases. However, the doping efficiency of NH 3 is smaller than that of N 2 . The use of NH 3 also induces a very large topological disorder. The present results give support to the view that active N doping in a-Ge:H originates from overcoordinated nitrogen atoms ͑N 4 ϩ ͒ without the need of one or more hydrogen neighbors. ͓S0163-1829͑96͒05020-5͔

No abstract