Defects and Microstructure in Optimized a-Si:Ge:H - New Results from Electron Spin Resonance Experiments

Abstract

ABSTRACTAmorphous silicon germanium alloys with improved properties for photovoltaic applications are investigated by electron spin resonance. Spin densities in this material are strongly reduced with optimized deposition conditions. Still the Ge dangling bond remains the dominating deep defect and the ratio of Ge over Si dangling bond defects is not much changed. The spin resonance spectra of these samples show distinctive differences from conventional material. The superposition signal can not be deconvoluted into modified Si- and Ge- dangling bond resonances as done previously. Instead a lineshape asymmetry or additional resonances are needed to deconvolute the spectra. The development of g-values with alloy composition indicate a more homogeneous chemical ordering in optimized material in agreement with other experimental data.