Temperature dependence of the mobility edge in amorphous silicon

Abstract

We report the first direct determination of the temperature dependence of the mobility edge ${E}_{c}$ from internal photoemission measurements on $a\ensuremath{-}\mathrm{S}\mathrm{i}$ Schottky barriers. A simultaneous measurement of the dc conductivity allows us to estimate the statistical shift of the Fermi level ${E}_{F}$. For undoped material, we find $\frac{d{E}_{c}}{\mathrm{dT}}=8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}\frac{\mathrm{eV}}{\mathrm{K}}$ and $\frac{d{E}_{F}}{\mathrm{dT}}=3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}\frac{\mathrm{eV}}{\mathrm{K}}$.