A dependence of the W/T ratio upon the dislocation density of MBE-grown GaAs buffer layers on Si substrates was reported. It was found that the W/T ratio strongly depended upon the dislocation density of the MBE-grown GaAs buffer layer, and the W/T ratio increased with a decrease in the dislocation density of the GaAs buffer layer grown onto Si substrates by MBE. AFM observation showed that on the surface of the MCE layer, a multi-fold spiral, which supplied the growth steps for the MCE was formed by single-fold spirals. In addition, it was also observed that the number of the single-fold spirals forming the multi-fold spiral was decreased as the dislocation density of GaAs/Si substrate was decreased, leading to decrease in the step density for the MCE. As a result, decrease in the number of the single-fold spiral dislocations results in increase in the W/T ratio.

Effect of Dislocation Density on Microchannel Epitaxy of GaAs on GaAs/Si Substrate. Y.S.Chang, S.Naritsuka, T.Nishinaga: Journal of Crystal Growth, 2010, 312[5], 629-34