ION IRRADIATION-INDUCED DEFECTS IN EPITAXIAL GAAS-LAYERS

We have investigated the effects of heavy ion irradiation on n-type Ga As layers, grown by molecular beam epitaxy (MBE). The ion beam we have used concerns protons (1 MeV), alpha particles (5.4 MeV), oxygen (25 MeV), iodine (200 MeV) and gold (253 MeV). The total fluence for each beam was 8 x 10(13), 1.9 x 10(12), 10(10), 10(9), 1.2 x 10(6) cm(-2), respectively. The induced damage is via displacement. Up to six differ ent groups of deep levels were induced but in the case of heavy ions, as for instance iodine and gold they were not well resolved. Identific ation of the induced deep levels was attempted by comparing their Arrh enius signature with those of known levels, cited in the literature. A nnealing experiments were also carried out and we have found that some of the defects recover at about 470 degrees K (200 degrees C). The an nealing kinetics is first order, which means that the recovery mechani sm is by close pair recombination rather than diffusion. (C) 1998 Else vier Science Ltd. All rights reserved.