Effect of ionization of impurity centres by electric field on the conductivity of superlattice

The electric field E(0) effect on ionization on impurity centres and on the conductivity of superlattices (SLs) has been studied theoretically. It is observed that as the field E(0) increases the current rises, reaches a maximum, then falls off, i.e. show a negative differential conductivity (NDC). Further increase in E(0) leads to an exponential rise of the current. This occurs around E(0) = 3 x 10(4) V cm(-1). Hence the current density field shows a 'N' shape characteristics as against the 'n' shape characteristics in the absence of impurity. (C) 1996 Academic Press Limited