Positron lifetimes in undoped or Si-doped (1.3 x 1018/cm3) liquid encapsulated Czochralski material were measured before and after bombardment with protons (15MeV, 1015/cm2). In the case of Si-doped material, a decrease in positron lifetime at temperatures of between 10 and 300K was attributed to a decrease in the positron diffusion length and to an increase in the number of effective shallow traps such as the GaAs antisite. The annealing of proton-induced defects exhibited a different behavior to that of electron-induced defects, and it was suggested that proton irradiation created more complicated defect complexes which contained vacancies rather than isolated vacancy-type defects, or the simple complexes which resulted from electron irradiation. At temperatures above 700K, proton-induced defects such as vacancy-type defects and simple vacancy complexes were almost entirely annealed out while Si-induced defects such as SiGa-VGa complexes could not be annealed out at temperatures above 973K.

Y.Itoh, K.H.Lee, H.Murakami, R.Iwata: Applied Physics A, 1995, 60[1], 57-60