Influence of multi wafer annealing of LEC GaAs substrates on the quality of epitaxial layers

The lateral distribution of dislocations and nonradiative recombination centers in buik LEC GaAs is reproduced in the epilayer. Combined ingot/multi wafer annealing reduces the excess As concentration at dislocations and generates As matrix precipitates. We find that the presence of matrix precipitates does not adversely affect the epitaxial layer quality. On the other hand layer defects correlated with substrate dislocations are still visible. Hence either the ingot/wafer annealing does not sufficiently reduce dislocation-correlated substrate defects migrating into the epilayer. Alternatively, nonradiative recombination centers are generated during epitaxial growth near dislocations propagating from the substrate into the epilayer.