Nitrogen radical adsorption on InAs (001) surface studied by scanning tunneling microscopy and x-ray photoelectronic spectroscopy

The adsorption of nitrogen (N) radicals (nitridation) on InAs (001) surface s has been studied by ultrahigh-vacuum scanning tunneling microscopy and x- ray photoelectronic spectroscopy. The nitridation proceeds as Langmuir adso rption. The N adsorption at 350 degrees C is faster than that at 100 degree s C, but N adsorption rates at 100 degrees C on InAs and GaAs are almost th e same. These results are explained as follows: at 350 degrees C, N radical s bond mainly with the topmost In atoms on an In-stabilized surface, and at 100 degrees C, N radicals replace As atoms in the topmost layer on an As-s tabilized surface, and subsequently bond with In atoms in the second layer. The amorphous 100 degrees C nitrided surface layer is found to have an ins ulating characteristic without surface states. (C) 1998 American Institute of Physics. [S0003-6951(98)03551-7].