DEEP LEVELS IN THE UPPER BAND-GAP REGION OF LIGHTLY MG-DOPED GAN

Deep levels in undoped and weakly Mg-doped n-type GaN films fabricated by metalorganic chemical vapor deposition were examined with deep lev el transient spectroscopy. Deep levels measured at 0.26 and 0.62 eV be low the conduction band were found in relatively low concentrations of similar to 2X10(13) cm(-3) in undoped GaN. Addition of small quantiti es of the Mg acceptor species by means of bis-cyclopentadienyl magnesi um (Cp(2)Mg) during growth corresponded to a significant increase in t he concentration of the level at 0.62 eV. The concentration of the sha llower level, found to be independent of the Cp(2)Mg addition, remaine d unchanged. These deep levels may detrimentally affect optical and el ectrical properties when fabricating p-type GaN. (C) 1996 American Ins titute of Physics.