Positron annihilation lifetime spectra were determined in a series of crystals of various conductivity types, and were analyzed by using numerical Laplace inversion techniques. It was found that the average positron annihilation rates in n-type and SI-type material

were almost the same, but were smaller than those in p-type material. It was noted that the width of the positron annihilation rate distribution in n-type and SI-type material was much broader than that in p-type material. The upper limit of the annihilation rate distribution varied from 3.96/ns for p-type samples to about 3.77/ns for n-type and SI-type samples. This indicated that, in n-type and SI-type samples, both In and P vacancies could trap positrons. However, in the case of p-type InP, the In vacancies alone were trapping sites. The charge state of VIn and VP was neutral.

Z.Q.Chen, X.W.Hu, S.J.Wang, S.Q.Li: Solid State Communications, 1996, 99[10], 745-9