Raman scattering and short range order in amorphous germanium

Variations in short range order of amorphous Ge films are determined from a combination of depolarized Raman scattering, optical absorption, and previous radial distribution function studies. An estimated minimum value of the bond angle width of Δθ ? 9°, obtained for evaporated, anneal stable a-Ge differs significantly from a recent EXAFS estimate. The maximum disorder observed in dc sputtered films deposited at ～90K indicates that an ～20% variation in bond angle width is possible in a-Ge. Substantial modification of the Raman spectrum of the low temperature film annealed at 300K also demonstrates that lower temperature structural relaxation processes involve changes in short range order.