Capture from free-carrier tails in the depletion region of junction barriers

Abstract

Junction experiments have been proposed in which measurements of depletion capacitance as a function of decreasing reverse bias are used to determine the energy level of a deep trap. Since deep levels in the depletion layer are filled from the free-carrier tail extending from the bulk, this process is slow to reach equilibrium. Calculation and experiment demonstrate this effect and it is emphasized that its neglect leads to serious misinterpretation.