Electron-drift-mobility measurements and exponential conduction-band tails in hydrogenated amorphous silicon-germanium alloys

摘要: We have measured the temperature dependence of electron drift mobility using time-of-flight technique for a series undoped hydrogenated amorphous silicon-germanium alloys with band gaps spanning range 1.47--1.72 eV. also developed techniques analyzing dispersion effects in such measurements, which permitted us to compare essentially all previous measurements our own. draw two main conclusions. First, there is substantial agreement between laboratories reduction due Ge alloying. Second, we are able account most features data standard multiple-trapping model by invoking only variations an exponential conduction-band-tail width ${\mathit{scrE}}_{\mathit{C}}^{0}$; find fair linear correlation this and optical gap ${\mathit{scrE}}_{\mathit{T}}$. The alloying upon microscopic attempt-to-escape frequency were relatively minor.