Impurity-to-band tunneling in semiconductors

Rate formulas for impurity-to-band tunneling from shallow and deep impurity levels are discussed. For the case of deep levels involving carriers bound to neutral impurity centers, it is shown that there is no substantial difference between the results of Anderson and Hoffman and those of Chaudhuri, Coon, Derkits, and Banavar. On the other hand, a different field dependence is found for the case of deep levels associated with carriers bound to charged impurity centers.