A new carrier compensation mechanism was investigated in N-doped films which had been grown by means of low-pressure metalorganic vapor-phase epitaxy. Photo-conduction spectrum measurements revealed the existence of deep defect levels which were located just above the center of the band-gap in N-doped and highly compensated films. Overall, the results revealed that these mid-gap deep levels acted as deep donors.

A.Ohki, Y.Kawaguchi, K.Ando, A.Katsui: Applied Physics Letters, 1991, 59[6], 671-3