Effect of dislocation density on microchannel epitaxy of GaAs on GaAs/Si substrate

We have reported the success in obtaining MCE-grown GaAs layers with wide dislocation-free region on Si substrate. In this paper, we report the dependence of the W/T ratio on the dislocation density of the MBE-grown GaAs buffer layer on Si substrate. It is found that the W/T ratio depends on the dislocation density of the MBE-grown GaAs buffer layer strongly, and the W/T ratio is increased with decrease in the dislocation density of the GaAs buffer layer grown on Si substrate 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 is 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.