EBIC contrast study of the recombination mechanism at dislocations in GaAs

AbstracL The energy bands associated with dislocationsin gallium arsenidecreate, even in the space charge region (SCR) of a Schottky diode, electric fields which can cancel the Schottky field near the dislocationline. Therefore, minority carriers created in these regions recombine at the dislocationline, giving rise to an EBIC contrast. Solution of Poisson's equationallows us to determine the variation of the dislocationcapture radius with depth in the SCR, and to obtain a quantitative estimate of the EBIC contrast. The theoretical results in which saturation effects can be introduced are compared with experimental ones obtained on both a and fl dislocationtypes. This comparison leads us to conclude that the saturation effect is not efficient in GaAs, and we suggest that it is probably cancelled by a current flowing along the dislocationline.