A new composition of matter is described, amorphous GaN.sub.1-xAs.sub.x:Mg, wherein 0<x<1, and more preferably 0.1<x<0.8, which amorphous material is of low resistivity, and when formed as a thin, heavily doped film may be used as a low resistant p-type ohmic contact layer for a p-type group III-nitride layer in such applications as photovoltaic cells. The layer may be applied either as a conformal film or a patterned layer. In one embodiment, as a lightly doped but thicker layer, the amorphous GaN.sub.1-xAs.sub.x:Mg film can itself be used as an absorber layer in PV applications. Also described herein is a novel, low temperature method for the formation of the heavily doped amorphous GaN.sub.1-xAs.sub.x:Mg compositions of the invention in which the doping is achieved during film formation according to MBE methods.
STATEMENT OF GOVERNMENTAL SUPPORT
 The invention described and claimed herein was made in part utilizing funds supplied by the U.S. Department of Energy under Contract No. DE-AC02-05CH1231 between the U.S. Department of Energy and the Regents of the University of California for the management and operation of the Lawrence Berkeley National Laboratory. The government has certain rights in this invention.