Effect of thermal annealing conditions on the microdefect formation in undoped GaAs single crystals grown by Czochralski method

The effect of thermal annealing conditions on the microdefect formation in undoped GaAs single crystals grown by the Czochralski method has been studi ed by X-ray diffraction and metallographic analyses. It is found that the s tandard heat treatments performed with the aim to relieve elastic stresses and to increase the homogeneity of wafers substantially affect microdefects formed in the crystal. Upon annealing, the microdefects in ingots and wafe rs exhibit different behavior. Prolonged annealing leads to an increase in the sizes of large microdefects but does not suppress the formation of smal l-sized microdefects. The latter defects are formed at T < 950 degrees C up on cooling from the annealing temperature, and their number strongly depend s on the density of dislocations, which serve as sinks for intrinsic point defects. (C) 2000 MAIK "Nauka/lnterperiodica".