INFLUENCE OF IRRADIATION CONDITIONS ON THE DEFECT FORMATION PROCESSES IN N-TYPE GAAS

Measurements of the capacitance of n-type GaAs films with n0 = 3 x 10(14) - 2 x 10(16) cm-3, irradiated with E = 0.9 - MeV electrons at THETA = 20-degrees-C, revealed familiar electron traps E1 - E5 and E8, whereas in the case of a film with n0 = 2 x 10(17) cm-3 there was an additional trap E3-beta. The efficiencies of formation of these traps were practically unaffected by variation of the electron beam intensity (I = 6 x 10(11) - 3 x 10(13) cm-2.s-1). The influence of the irradiation temperature (THETA) on the processes of formation in GaAs were analyzed for films with n0 almost-equal-to (1 - 3) x 10(15) cm-3. It was established that at THETA almost-equal-to 300-degrees-C the thermal annealing during the irradiation process reduced strongly the efficiency of formation of the E traps so that the main contribution to the changes in the properties of the material was made by traps of the X type. It was shown for the first time that a further increase in THETA right up to 550-degrees-C had practically no influence on the spectrum of the radiation-generated electron traps, which consisted of two main centers: X1 and X2 with E(a) = 0.38 and E(a) = 0.76 eV, respectively. An analysis was made of the kinetics of accumulation of these centers by irradiation at THETA = 400-degrees-C and their main parameters were determined. The results of irradiation at THETA = 300-degrees-C were found to be almost the same as those produced by irradiation at THETA = 20-degrees-C and annealing at 300-degrees-C.