Positron annihilation lifetime and photo-induced current transient spectroscopies were employed to study the formation of compensation defects in undoped InP under different annealing processes with pure-P ambience and iron-phosphide ambients, respectively. The different annealing ambiences convert the as-grown n-type undoped InP into two types of semi-insulating states. The positron average lifetimes of as-grown InP, pure-P semi-insulating InP, and iron phosphide semi-insulating InP were found to be 246, 251 and 243ps, respectively, which were all longer than the bulk lifetime of 240ps, indicating the existence of vacancy-type positron-trapping defects. For as-grown InP, VInH4 complexes were the dominant defects. They dissociated into VInHn (n = 0 to 3) acceptor vacancies under pure-P ambience annealing, compensating the residual shallow donors and turning the material semi-insulating. In forming iron-phosphide semi-insulating InP, diffusion of Fe into VIn complexes under iron-phosphide ambience annealing produces the substitutional compensation defect FeIn, causing a shorter positron average lifetime. The photo-induced current transient spectroscopic measurements showed that a group of vacancy-type defects was suppressed by Fe diffusion during the annealing process, which was in good agreement with the positron annihilation lifetime results.

Effects of Annealing Ambient on the Formation of Compensation Defects in InP. A.H.Deng, P.Mascher, Y.W.Zhao, L.Y.Lin: Journal of Applied Physics, 2003, 93[2], 930-2