Second-harmonic generation as probe for structural and electronic properties of buried GaP/Si(001) interfaces

TL;DR

This paper demonstrates that optical second-harmonic generation can effectively probe the buried GaP/Si(001) interface, revealing interface quality and defects through polarization-dependent anisotropy measurements, useful for in-situ monitoring.

Contribution

It introduces SHG as a non-invasive, in-situ optical technique to assess interface quality and detect defects like anti-phase domains and twins in GaP/Si interfaces.

Findings

Strong isotropic SHG component indicates interface quality.

SHG anisotropy correlates with atomic-scale interface features.

Technique enables in-situ monitoring during growth.

Abstract

Optical second-harmonic generation is demonstrated to be a sensitive probe of the buried interface between the lattice matched semiconductors gallium phosphide and silicon with (001) orientation. Rotational anisotropy measurements of SHG from GaP/Si show a strong isotropic component of the response not present for pure Si(001) or GaP(001). The strength of the overlaying anisotropic response directly correlates with the quality of the interface as determined by atomically resolved scanning transmission electron microscopy.Optical second-harmonic generation is demonstrated to be a sensitive probe of the buried interface between the lattice matched semiconductors gallium phosphide and silicon with (001) orientation. Rotational anisotropy measurements of SHG from GaP/Si show a strong isotropic component of the response not present for pure Si(001) or GaP(001). The strength of the overlaying anisotropic response directly correlates with the quality of the interface as determined by atomically resolved scanning transmission electron microscopy. Systematic comparison of samples fabricated with different growth modes in metal organic vapor phase epitaxy reveals that the anisotropy for different polarization combinations can be used as a selective fingerprint for the occurrence of anti-phase domains and twins. This all-optical technique can be applied as an {\it in-situ} and non-invasive monitor even during growth. Systematic comparison of samples fabricated with different growth modes in metal organic vapor phase epitaxy reveals that the anisotropy for different polarization combinations can be used as a selective fingerprint for the occurrence of anti-phase domains and twins. This all-optical technique can be applied as an {\it in-situ} and non-invasive monitor even during growth.