Deposition of A-Ge:H by Gef4/H 2 Glow Discharge

Abstract

ABSTRACTHydrogenated amorphous germanium (a-Ge:H) thin films have been grown by DC proximity glow discharge deposition using GeF,/H2 as the source gas mixture. The film growth rate decreases with increasing substrate temperature because of the temperature activation of the competitive “etching” reaction: GeF, + Ge -2GeF 2. At sufficiently high substrate temperature and GeF4, partial pressure, this reaction dominates and film growth is suppressed. The hydrogen fraction in the source gas mixture appears to determine the extent of decomposition of GeF4. The deposition rates of germanium films grown from SiF4/GeF4/H2 and Ar/GeF4,/H2 under similar gas fraction and discharge power conditions are compared. The results suggest that Si species catalyze the deposition of Ge in SiF4/GeF4/H2 glow discharges. a-Ge:H films grown from GeF4/H2 have optical, electronic and structural properties similar to films grown by GeH, glow discharge.