Semi insulating (SI) InP wafers of 50 and 75mm in diameter can be obtained by annealing of undoped liquid encapsulated Czochralski (LEC) InP at 930℃ for 80h.The annealing ambient can be pure phosphorus (PP) or iron phosphide (IP).The IP SI InP wafers have good electrical parameters and uniformity of whole wafer.However,PP SI InP wafers exhibit poor uniformity and electrical parameters.Photoluminescence which is subtle to deep defect appears in IP annealed semi insulating InP.Traps in annealed SI InP are detected by the spectroscopy of photo induced current transient.The results indicate that there are fewer traps in IP annealed undoped SI InP than those in as grown Fe doped and PP undoped SI InP.The formation mechanism of deep defects in annealed undoped InP is discussed.
