Evolution of surface structure during carbon doping in the metal-organic vapor-phase epitaxial growth of GaAs

A comprehensive study of carbon doping in GaAs in metal-organic vapor-phase epitaxy (MOVPE) process, combining growth, electrical and morphological studies, is presented. The impact of carbon incorporation on the development of surface morphology has been systematically investigated. Heavily carbon-doped (similar to 10(20) cm(-3)) layers with different thickness were grown to study the evolution of the surface morphology. Carbon was incorporated into GaAs using two different carbon-doping sources, trimethylarsenic (TMAs) and CCl4, to create different surface chemical environments during the growth. TMAs-doped GaAs films show step pinning, defects, and island growth, while CCl4-doped GaAs surfaces typically have a terrace structure. The micrographic images were quantitatively analyzed through the determination of the height-height and height-difference correlation functions which yields both the short-and long-range surface structures. The change of the correlation length, as well as direct evidence from surface images, indicates a change of growth mode during the growth of TMAs-doped GaAs film on singular substrates. A description of the chemical influences during carbon doping on the growth front evolution is presented. The surface-adsorbed methyl groups and not the carbon impurity itself at the growth front determine the change of the growth mode.