Controlling facets and defects of InP nanostructures in confined epitaxial lateral overgrowth

Abstract

The selective area growth technique, confined epitaxial lateral overgrowth (CELO), enables the growth of lateral III-V heterojunctions integrated on mismatched substrates. In CELO, effective control of facet shapes, as well as defect-free growths are essential to fabricating high-quality nanostructures with custom geometries. Here, the effects of growth temperature, V/III ratio, template alignments, and substrate orientations on the observed facets and defect densities in CELO grown InP and related materials on InP substrates are investigated. The nanostructure facets and defects are determined using a combination of plan-view and cross-sectional transmission electron microscopy. For homoepitaxial CELO growth on InP (100) substrates, growth temperatures below $575{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$, and high V/III ratios of 450 aid in increasing the surface areas of the {111}B facets, while reducing defect densities. Further, by changing template alignments, the effective areas of overgrowth can be tuned, and defects can be lowered, with templates aligned along $[0\overline{1}0]$ yielding the largest defect-free areas. By aligning templates in the $[\overline{1}10]$ orientation on a (110) InP substrate, near defect-free overgrowth with perfectly flat perpendicular single ($1\overline{1}$ 0) facets can be achieved. This is an essential feature to enable the growth of lateral III-V heterojunctions, as is demonstrated by growing InP/InGaAs CELO heterojunctions with {110} facets.