Theory of Poole-Frenkel conduction in low-mobility semiconductors

Abstract A new expression is derived for the current produced by a high electric field in a low-mobility semiconductor, taking into account the mechanism of Poole-Frenkel emission from a Coulombic trap, the mobility of the carrier after emission into the conduction band, and the zero-field statistical distribution of carriers between conduction band, donor states and compensating acceptor states. Differences between these and earlier formulae are examined, and arguments presented for the different regimes of applicability. Recent data on amorphous germanium are considered, using the various formulae, and it is concluded that high-field transport measurements alone are insufficient to define uniquely the parameters of such theories.