On the EBIC bright contrast at the dot-and-halo features in GaAs

The dot-and-halo features detected by EBlC in Si-doped bulk GaAs have been studied quantitatively by energy-dependent EBIC to determine the influence of the width of the space charge region of the EBIC Schottky diode on the formation of the negative (bright) EBIC contrast. It has been found that in the majority of the cases the bright contrast is mostly due to an increase of the width of the space charge region (i.e. depletion of shallow donor impurities) rather than to an increase of the diffusion length (i.e. depletion of deep non-radiative impurities).