Monolithic Integration of AlGaAs Distributed Bragg Reflectors on Virtual Ge Substrates via Aspect Ratio Trapping

TL;DR

This paper demonstrates the successful monolithic growth of high-quality AlGaAs DBRs on silicon substrates using an aspect ratio trapping technique to form a virtual Ge layer, enabling potential optoelectronic integration.

Contribution

It introduces a novel method for growing high-quality GaAs/AlGaAs DBRs on Si substrates via ART Ge layers, reducing defects and enabling future VCSEL fabrication.

Findings

Reflectivity spectra comparable to bulk GaAs-based DBRs

Reduced antiphase domain formation in GaAs on ART-Ge/Si

Etch pit density ranging from 10^5 to 6 x 10^6 cm^(-2)

Abstract

High quality AlxGa1-xAs distributed Bragg reflectors (DBRs) were successfully monolithically grown on on-axis Si (100) substrates via a Ge layer formed by aspect ratio trapping (ART) technique. The GaAs/ART-Ge/Si-based DBRs have reflectivity spectra comparable to those grown on conventional bulk off-cut GaAs substrates and have smooth morphology, and good periodicity and uniformity. Anitphase domain formation is significantly reduced in GaAs on ART-Ge/Si substrates, and etch pit density of the GaAs base layer on the ART-Ge substrates ranges from 10^5 to 6 x 10^6 cm^(-2). These results paved the way for future VCSEL growth and fabrication on these ART-Ge substrates and also confirm that virtual Ge substrates via ART technique are effective Si platforms for optoelectronic integrated circuits.