THE INFLUENCE OF GAAS CRYSTAL COMPOSITION ON THE FEATURES OF MATRIX MICRODEFECTS

Associations of intrinsic point defects in as-grown LEC and HB GaAs single crystals undoped and doped with In, Si, Te and Zn have been studied. Dislocation loops as well as clusters of intrinsic point defects, which were not visible in TEM, were revealed and investigated by an X-ray diffuse scattering method. The maximum number of interstitial atoms forming these microdefects was not more than 10(17) CM-3. We found that interstitials forming the diffuse ''clouds'' coagulated into dislocation loops in GaAs doped with donor impurities when the free electron concentration n was more than n(c) = 3 x 10(18) CM3, thus increasing the supersaturation of arsenic interstitials in crystals and leading to an increase in the value of n(c). The experimentally revealed features of microdefects in the as-grown GaAs single crystals have been analysed using the supposition that cluster forming interstitials interact electrostatically and elastically.