Spontaneous and laser-enhanced halogen etching of GaAs(110)

Abstract

We review studies of surface morphologies associated with Cl and Br etching of GaAs(110) via thermal and laser activation, with an emphasis on the former. Using atomic-resolution scanning tunnelling microscopy, we examine the chemisorption structures, etch pit development and growth on terraces, step etching, the concentration dependence of various etching pathways, and the etching yields in the temperature range of 300-800 K. Surface structural changes are correlated with the underlying reaction processes and the stabilities of steps. Etch pit morphologies achieved by nanosecond laser-pulse irradiation of Br-covered GaAs(110) are compared with those obtained in spontaneous etching. We discuss etching mechanisms in light of the observed differences in etching morphology.

Laser machining fundamentals: micro, nano, atomic and close-to-atomic scales

“…Laser fluence can be increased for a higher efficiency in the LID stage, but it may also induce small defects, with a dimension of 1-4 surface unit cells on the second layer [78]. More details about the halogen-based CALID of GaAs have been reviewed in 1998 [79]. This method is currently investigated in the frame of quantum theory, and the calculation shows that the desorption probability would saturate within hundreds of femtoseconds after excitation and has a superlinear dependence on the lifetime of excited states [80].…”