ON THE REACTION-MECHANISM OF GAAS MOCVD

The reaction mechanism of TMG and AsH3 on a GaAs substrate is discussed. The reaction of TMG was affected sensitively by the surface of GaAs substrate, and the surface reaction was quite different from the pyrolytic reaction of TMG in the vapor phase. Also, it became clear that the GaAs substrate and Ga had a catalytic action on AsH3 decomposition. The catalytic action may occur at lower temperatures, even down to 200°C. Ga atoms also seem to be transported in the furnace in some form to a separate place. When TMG and AsH3 were introduced simultaneously, an intermediate compound with infrared absorption peak at 2080 cm-1 was formed. The final species to stick to the (111)A, which shows the fastest growth rate in normal MOCVD, is not yet clear. © 1990.