Impurity‐to‐band tunneling in Hg1−xCdxTea)

Abstract

Theoretical modeling of deep level impurity‐to‐band tunneling is carried out in the framework of time‐dependent perturbation theory. The basic method is formulated by analogy with the hydrogen ionization problem in a uniform electric field. Based on the WKB approximation, an asymptotic expansion for the wave function in the space charge region is used to derive explicit expressions for the transition matrix element W, assuming a Coulomb potential for the localized center. Comparison with the only known experimental estimate (gold doped silicon for which ‖W‖2∠10−47 erg2 cm3) yields a reasonably close agreement with our theoretical value. Furthermore, the theoretical result is found to be markedly insensitive to the choice of the trap potential. Further improvements in the theory can be accomplished by taking band nonparabolicity into account and relaxing the constant field approximations. Application of the theory to find the generation–recombination rate for this process leads to a pronounced peak in the I‐V characteristic for a set of device parameters chosen to approximate the case of an InSb diode in which such a peak has been observed experimentally.