Identification of vacancy-type defects in as-grown InP by positron annihilation rate distribution measurements

The positron annihilation lifetime spectra were measured on a series of InP crystals with different conduction type and carrier concentration and analyzed by numerical Laplace inversion technique. Three noticeable features were observed: 1)the average positron annihilation rate 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 (ARD) in n- and SI-type is much broader than that in p-type; 3)the upper limit of ARD was shifted from 3.96 for p-type to about 3.77ns(-1) for n-type and SI-type InP. These results indicate that in n- and SI-type InP, both Indium and Phosphorus vacancies (V-In, V-P) can trap positrons, bur in p-tppe InP, only In-vacancy is the trapping site. The charge state of V-In and V-P is neutral determined by the temperature experiment.