Ion-induced nitridation of GaAs(100) surface

The ion-induced nitridation of GaAs(1 0 0) using 1.2 keV N-2(+) ion beams has been investigated using in situ X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Ga-rich surfaces produced by Ar+ cleaning, promote initial nitridation and formation of GaN. The dependence of [N]/[Ga] and [As]/[Ga] atomic ratios on substrate temperature, nitridation time, and nitrided layer depth suggest that the process is self-limiting. The degree of nitridation increases with the temperature, but decreases again at higher temperatures (> 450 degreesC). Smooth nitrided layers are formed between room temperature and 450 degreesC. For nitridation at T = 600 degreesC however, the aggregation of GaAs1-xNx results in the roughening of the nitrided surfaces. Diffusion, sputtering, and decomposition effects in the nitridation process are considered, and the mechanisms of GaAs1-xNx formation are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.