Preparation of Semi-Insulating Material by Annealing Undoped InP

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-undoped SI InP. The formation mechanism of deep defects in annealed undoped InP is discussed.