ATOMIC LAYER ETCHING OF GAAS(110) WITH BR-2 STUDIED BY SCANNING TUNNELING MICROSCOPY

Scanning tunneling microscopy studies of GaAs(110) exposed to Br2 at 720 K show preferential etching at single-height [112BAR] and [001] steps with little etching at double-height steps. Etching in the [110BAR] direction is at least approximately 4.5 times faster than in the [001] direction, producing rectangular etch pits. For higher Br2 exposures, etching is dominated by single-height step flow but triangular double-layer etch pits also form on extended terraces.