Persistent photoconductivity was detected in N-doped p-type material at low temperatures. The increase in conductivity after illumination appeared to be due to a metastable population of holes which were in thermodynamic equilibrium with hydrogenic acceptors with a reduced activation energy. It was concluded that the experimental evidence indicated the occurrence of a DX-like center behavior for holes.

J.Hari, M.D.Ringle, Y.Fan, R.L.Gunshor, A.V.Nurmikko: Applied Physics Letters, 1994, 65[25], 3230-2