Drastic Reduction of Dislocation Density in Semipolar ($11\bar{2}2$) GaN Stripe Crystal on Si Substrate by Dual Selective Metal--Organic Vapor Phase Epitaxy

A drastic reduction of the dislocation density in a semipolar ($11\bar{2}2$) GaN stripe on a patterned Si substrate was achieved by the two-step selective growth of a GaN stripe. After depositing a SiO2mask on the ($11\bar{2}2$) and ($000\bar{1}$) faces of a GaN stripe grown on a (113) Si substrate, GaN was regrown only on the ($\bar{1}\bar{1}22$) face. The dislocation density estimated from the dark-spot density in a cathodoluminescence (CL) image greatly decreased from $4.0\times 10^{8}$ to $1.0\times 10^{5}$/cm2in the regrowth region. A transmission electron microscopy (TEM) image also verified that there were no dislocations at the regrowth interfaces.