Epitaxial lateral overgrowth of Ga_xIn_1 − xP toward direct Ga_xIn_1 − xP/Si heterojunction

Abstract

The growth of GaInP by hydride vapor phase epitaxy (HVPE) was studied on planar GaAs, patterned GaAs for epitaxial lateral overgrowth (ELOG), and InP/Si seed templates for corrugated epitaxial lateral overgrowth (CELOG). First results on the growth of direct GaInP/Si heterojunction by CELOG is presented. The properties of GaxIn(1 − x)P layer and their dependence on the process parameters were investigated by X‐ray diffraction, including reciprocal lattice mapping (XRD‐RLM), scanning electron microscopy equipped with energy‐dispersive X‐ray spectroscopy (SEM‐EDS), photoluminescence (PL), and Raman spectroscopy. The fluctuation of Ga composition in the GaxIn(1 − x)P layer was observed on planar substrate, and the strain caused by the composition variation is retained until relaxation occurs. Fully relaxed GaInP layers were obtained by ELOG and CELOG. Raman spectroscopy reveals that there is a certain amount of ordering in all of the layers except those grown at high temperatures. Orientation dependent Ga incorporation in the CELOG, but not in the ELOG GaxIn(1 − x)P layer, and Si incorporation in the vicinity of direct GaxIn(1 − x)P/Si heterojunction from CELOG are observed in the SEM‐EDS analyses. The high optical quality of direct GaInP/Si heterojunction was observed by cross‐sectional micro‐PL mapping and the defect reduction effect of CELOG was revealed by high PL intensity in GaInP above Si.

Topical review: pathways toward cost-effective single-junction III–V solar cells

“…Defect trapping by selective area epitaxy (SAE) is another type of popular growth technique that has been studied extensively for III-V epitaxy on Si. Defect trapping techniques such as epitaxial lateral overgrowth (ELOG) [137,138,[140][141][142][143][144][145][146][147][148][149][150][151] and aspect ratio trapping (ART) [97,98,[152][153][154][155][156][157][158][159][160][161][162][163] are compatible with SAE, and have been shown to achieve effective dislocation filtering. As illustrated in figure 9(a), by aligning the mask openings in specific crystallographic directions to maximize lateral growth, the ELOG technique confines dislocations within the mask opening window, resulting in reduced dislocation density in the overgrown layer.…”

“…As shown in figure 9(b), abrupt InP/Si interface is formed by downward growth of the ELOG InP layer instead of direct InP nucleation on the Si surface, which is avoided by the high growth selectivity in HVPE. With the CELOG technique, the group has reported highquality HVPE-grown InP/Si and GaInP/Si interfaces, which can potentially be utilized for InP-based tandem solar cells on Si [138,143,144,146,147,149,150].…”