PASSIVATION VERSUS ETCHING - ADSORPTION OF I-2 ON INAS(001)

Halogen adsorption on certain III-V semiconductor surfaces forms order ed overlayers, while other surfaces etch. The microscopic mechanism un derlying this behavior is investigated by comparing the adsorption of I-2 on In- and As-terminated InAs(001) surfaces. On the In-terminated surface, a well-ordered (1 x 1) structure forms and all of the iodine attaches to In. The As-terminated surface becomes disordered, however, and iodine attaches to both In and As. These observations can be expl ained by assuming that iodine initially bonds to In atoms, whether the y are in the first or the second layer.