The solid-phase crystallization mechanism of hydrogenated amorphous silicon–germanium alloy films

We have investigated the solid-phase crystallization (SPC) process of a-Si1−xGex:H (x=0,0.21,0.67) alloy films by using X-ray diffraction and electron spin resonance measurements. The films were deposited on Corning 1737 glass at 200°C in a plasma-enhanced chemical vapor deposition system using SiH4 and GeH4 gases. The deposited films were then annealed to be crystallized at 600°C in a N2 atmosphere. The variation of spin densities due to the annealing was found to be strongly related to the variation in the crystalline fraction of the films. It was observed that the SPC process was dominated by Ge dangling-bonds rather than Si dangling-bonds for Ge-rich samples (x=0.21 and 0.67). Furthermore, the H evolution time from Ge–H bond for x=0.67 film was significantly faster than for the x=0.21 film, which was attributed to the composition-dependent Ge–H dissociation energy.