Coalescence of GaP on V-Groove Si Substrates

Here, we study the morphology and dislocation dynamics of metalorganic vapor phase epitaxy (MOVPE)-grown GaP on a V-groove Si substrate. We show that Si from the substrate stabilizes the (0 0 1) GaP facet, which is critical for achieving coalescence. The SiNx caps covering the (0 0 1) tops of the V-grooves must be sufficiently small for the 3 x 1 GaP surface reconstruction caused by Si to continue to influence the GaP coalescence while the V-grooved sidewalls are covered. If the SiNx caps are too large, (1 1 1) diamond faceting develops in the GaP, and coalescence does not occur. On samples where coalescence is successful, we measure a root-mean-square roughness of 0.2 nm and a threading dislocation density of 5 x 10^7 cm^-2. Dislocation glide was found to begin during coalescence through transmission electron microscopy. With further TDD reduction, these GaP on V-groove templates will be suitable for III-V optoelectronic device growth.