DISLOCATION EFFECT IN DIFFUSION OF COPPER IN THERMALLY CONVERTED GALLIUM ARSENIDE

The effect of dislocations on the diffusion behaviour of copper in gallium arsenide has been studied, using crystals that have turned from n- to p-type on annealing due to copper acceptor formation. The acceptor density, which is determined from photoluminescence and conductivity measurements, augments with increasing dislocation density, and can be reversibly altered by further annealing. From this it is shown quantitatively that dislocations act as sources and sinks respectively for the diffusion and precipitation of copper in GaAs, and for 600°C a diffusion coefficient of 5 × 10-10 cm2 sec-1 has been found. Values of the same order have been obtained by extracting copper from GaAs in gallium, and have also been confirmed from literature data. Finally, indications have been found which show that copper diffuses much faster along dislocations than in dislocation-free bulk material. © 1969.