Electron drift mobility in amorphous Si: H

Abstract

The ‘time of flight’ technique has been employed to study the transient photoconductivity due to excess electron carriers in amorphous Si:H, over a wide range of temperature and electric field. The data are analysed in terms of the temperature/field dependence of the carrier transit time, and also in terms of the variation in pulse shape with temperature. In both cases, the behaviour suggests interactions with a tail of states extending about 0·15 eV from the band edge and showing an almost linear variation of trap density with energy over at least the range 0·085 to 0·145 eV. The capture cross-section of the centres is estimated to be of order 10⁻¹⁷–10^−l6cm². Interaction with states beyond the tail is comparatively weak, and is dominated by deep trapping into centres believed to be dangling bonds.