Critical volume fraction of crystallinity for conductivity percolation in phosphorus-doped Si:F:H alloys

We have used Raman scattering to deduce the volume fraction of crystallinity for the highly phosphorus-doped glow-discharge Si:F:H alloys. The measured critical volume fraction at the onset of rapidly increased conduction in this two-phase system of microcrystallites embedded in an amorphous matrix is 0.18. This value coincides with the theoretical percolation limit and serves to explain the conduction process in these two-phase materials which are useful as contacts in amorphous solar cells.