Published online by Cambridge University Press: 26 February 2011
In the present paper a study on the semiconductor properties of a-Ge:Sn and a-Ge:Sn:H films is presented. The films were prepared by the rf sputtering method on substrates held at 180 C. The characterization includes composition, structure, and the transport and optical properties. The role and influence of hydrogen on the properties of the alloy have been established for the first time. The main results of the work follow, a) The addition of Sn narrows the optical band gap of a-Ge. b) The hydrogenated material posseses an activated type dark conductivity. c) No photoconductivity (AM 1 conditions) was detected in any of the alloyed films. d) At high Sn concentrations the metal segregates. e) No Sn-H absorption bands were detected in the infrared transmission spectra of hydrogenated samples (400 – 4000 cm−1 wavenumber range).