Direct Measurement of the Bulk Density of Gap States in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>n</mml:mi></mml:math>-Type Hydrogenated Amorphous Silicon

Abstract

The first direct measurement is reported of the bulk density of deep states in $n$-type $a$-Si: H. The spectral distribution is considerably different from previous field-effect and $C\ensuremath{-}V$ measurements and the overall density is much lower than has previously been reported. The states seen in these samples appear to be extrinsic and suggest that the extrapolated total density of deep states in pure $a$-Si: H may be less than ${10}^{15}$ ${\mathrm{cm}}^{\ensuremath{-}3}$.