LAYER-BY-LAYER GROWTH-MECHANISM OF ALXGA1-XP GROWN BY GAS-SOURCE MBE

The layer-by-layer growth process of AlxGal1-xP (0 less-than-or-equal- to x less-than-or-equal-to 1) was investigated by observing the reflec tion high energy electron diffraction intensity oscillations of the sa mples during growth. The damping of the oscillations were examined and it was found that there were three stages in the damping process. The damping behavior depended on the Al composition. Gallium-rich composi tions (x = 0.23 and 0.37) had a smaller damping rate than that of GaP. Aluminum-rich compositions (x > 0.5) clearly showed the three stages in the damping process, and the observed number of oscillations decrea sed with increasing Al composition. We propose a model for the growth process of AlxGa1-x P. For Ga-rich compositions the layer-by-layer gro wth is enhanced by Al atoms, which reduce the average terrace size. Fo r Al-rich compositions, where nucleation dominates, the surface roughn ess is diminished by Ga atoms which migrate and fill the kink-sites.