Persistent photocurrents in p-type N-doped epilayers, grown onto GaAs by means of molecular beam epitaxy, were studied. They were observed to occur at up to room temperature in some samples, with a decay time that ranged from several minutes to hours. A typical decay consisted of an initial stretched-exponential transient, and a subsequent slower transient. It was demonstrated that the persistent photocurrent had 2 components; one of which originated from the presence of metastable centres in the ZnSe layer at the hetero-interface. The other arose from the tunnelling of trapped holes from a 2-dimensional quantum well at the hetero-junction.

Investigation of Persistent Photoconductivity in Nitrogen-Doped ZnSe/GaAs Heterojunctions Grown by MBE. D.Seghier, H.P.Gislason: Journal of Crystal Growth, 2000, 214-215, 511-5