INDIUM AND GALLIUM P-TYPE DOPING OF HYDROGENATED AMORPHOUS-GERMANIUM THIN-FILMS

Hydrogenated amorphous germanium films have been p-type doped with indium and gallium. The room-temperature dark dc conductivity of the films has been found to change by several orders of magnitude within the studied dopant atomic concentration range (approximately 3 X 10(-5) to approximately 1 X 10(-2)). The conductivity change from n to p type for the more heavily doped materials indicates effective p-type doping. The hydrogen content and the optical gap of the doped films, on the other hand, remain essentially unchanged with respect to the undoped material. For the most doped samples, signs of metallic segregation have been detected in the case of gallium doping. Metallic segregation is not apparent for indium-doped samples.