Deep donor model for the persistent photoconductivity effect

Publisher Website
Google Scholar
Abstract
It is proposed that a persistent photoconductivity (PPC) effect is universally produced by deep donors. The general requirements of a class of models which explains the PPC effect in semiconductors are discussed. In particular, donor dopants such as Si and Te in Ga1−xAlxAs with x∼0.3 are conjectured to be deep and responsible for the PPC effect attributed to DX centers consisting of donor-vacancy pairs. It is shown that the Si donor has properties which explain the known data attributed to the DX center; these data include (1) the slow capture rate at low temperatures, (2) the thermally activated capture rate at high temperatures, and (3) the shape of the photoexcitation cross section. However, in contrast with the DX-center model, the deep donor model does not require a high trapped vacancy concentration ([V]∼1018 cm−3) to explain the PPC effect in highly doped semiconductors.