SYNCHROTRON-RADIATION PHOTOEMISSION SPECTROSCOPY STUDIES OF THE THERMAL NITRIDATION OF GAAS(100) WITH AMMONIA

The thermal nitridation of GaAs(100) with ammonia was investigated by synchrotron radiation photoemission spectroscopy and atomic force micr oscope. This study revealed the chemical composition, chemical states, and morphological changes in the nitridated surface layer. We observe d that ammonia can be decomposed to an activated nitrogen atom above 7 00 degrees C forming GaN an the surface. Thermally nitridated layers w ere composed of metallic Ga and GaN islands that are elongated along t he [011] direction to relax the tensile strain in the [011] direction. As the nitridation temperature increased, the composition of GaN incr eased in the nitridated layer due to the efficient thermal decompositi on of NH3 and the subsequent incorporation of the N atom into the meta llic Ga. The surface morphology of the nitridated layer, on the other hand, became substantially roughened at higher temperatures. (C) 1998 American Vacuum Society.