IDENTIFICATION OF VACANCY-TYPE DEFECTS IN AS-GROWN INP BY POSITRON-ANNIHILATION RATE DISTRIBUTION MEASUREMENTS

Positron annihilation lifetime spectra have been measured on a series of InP crystals with different conduction types and carrier concentrat ions and analysed by numerical Laplace inversion technique. Three noti ceable features were observed: (1) the average positron annihilation r ate in n and SI-type InP is nearly the same but smaller than that in p -type InP; (2) the width of positron annihilation rate distribution (A RD) in n-and SI-type is much broader than that in p-type; (3) the uppe r limit of ARD was shifted from 3.96 for p-type to about 3.77 n s(-1) for n-type and SI-type InP. These results indicate that in n- and SI-t ype InP, both indium and phosphorus vacancies (V-In, V-P) can trap pos itrons, but in p-type InP, only In-vacancy is the trapping site. The c harge state of V-In and V-P is neutral as determined by the temperatur e experiment. Copyright (C) 1996 Published by Elsevier Science Ltd.