Deposition and characterization of polymorphous germanium films prepared by low frequency PECVD

In this work we have deposited polymorphous germanium (pm-Ge:H) thin films by low frequency plasma enhanced chemical vapor deposition (LF-PECVD). We have studied the effect of the deposition pressure on the structural and electric characteristics of the films. Atomic force microscopy was used to analyze the surface roughness of the pm-Ge:H films, while transmission electron microscopy was used to observe the cross section. The temperature dependence of conductivity (sigma(T)), deposition rate (V-d), activation energy (E-a) and the temperature coefficient of resistance (TCR) were extracted on the pm-Ge:H films deposited at different pressure values. An optimal pressure range was found, in order to produce pm-Ge:H films with high E-a and TCR which are key parameters for thermal detection applications. (C) 2012 Elsevier B.V. All rights reserved.