LAYER-BY-LAYER ETCHING OF GAAS(110) WITH HALOGENATION AND PULSED-LASER IRRADIATION

We have investigated the effect of laser irradiation on the terrace mo rphology of Br-covered GaAs (110). Layer-by-layer etching of GaAs (110 ) is demonstrated through laser-induced etching and atomic desorption. Nanosecond pulsed-laser irradiation (h nu=2.3 eV, pulse power similar to 35 mJ cm(-2)) of Br-GaAs (110) initially produces a high density o f small, single-layer etch pits as Br is consumed. Continued laser irr adiation causes Ga and As desorption from pit edges so that pits grow and thereby remove the remnant of the top GaAs layer. When there is Br on the surface, pit growth reflects the Br chemisorption structure (e longated along [001]) but subsequent atom desorption favors growth alo ng [110]. (C) 1998 American Vacuum Society.