WAVELENGTH DEPENDENCE OF UV LASER SELECTIVE ALXGA1-XAS GROWTH VIA ADLAYER STIMULATION IN OMVPE

UV-stimulated organometallic vapor phase epitaxy (OMVPE) growth of AlG aAs from trimethylgallium, trimethylaluminum and arsine at 500 degrees C was studied using a wavelength-tunable pulsed laser in the range 23 5-255 nm. We demonstrate that the high growth contrast of 3.2:1 is due to the photostimulation of adlayer reactions at these wavelengths. Un der our growth conditions, the adlayer stimulation exhibits a waveleng th edge at 252 nm, above which the enhanced growth rate drops abruptly to zero. The s-polarized laser beam induces a pronounced periodic sur face structure in all cases, which is quantitatively examined by atomi c force and scanning electron microscopy. The structural and optical q ualities of the selectively grown layers are determined by Raman and p hotoluminescence spectroscopy. (C) 1998 Elsevier Science B.V. All righ ts reserved.