Bond-Orbital Model of Two-hole Laser-Induced Desorption from GaP (110)

Abstract

The widespread application of lasers in semiconductor processing has produced a voluminous literature on the mechanisms of laser desorption and ablation. There are significant disagreements, however, about the extraordinarily complex physical mechanisms underlying laser desorption and ablation. Here we discuss recent experiments and a model of a particularly simple case: desorption of Ga+ and Ga° by selective excitation of a surface electronic state on GaP (110). By choosing the electronic channel leading to desorption, and by monitoring the condition of the surface, one can determine accurately the threshold fluence above which the surface electronic structure is irreversibly altered by laser ablation. Below this threshold, desorption occurs at isolated defect sites and at perfect three-fold coordinated surface sites. This two-hole laser-induced desorption and ablation can be described by a bond-orbital model of electronic structure.