Selective Epitaxial Growth of GaAs on Ge Substrates with a SiO2 Pattern

TL;DR

This paper demonstrates a method for selectively growing high-quality GaAs films on Ge substrates using a SiO2 mask, optimizing growth conditions to achieve precise patterning and good material properties.

Contribution

It introduces an optimized growth process enabling fully selective epitaxial GaAs growth on Ge with controlled pattern sizes and minimized defects.

Findings

Successful selective GaAs growth on Ge with SiO2 masks

Growth process reduces anti-phase domains and loading effects

High-quality GaAs characterized by X-ray diffraction and photoluminescence

Abstract

We have selectively grown thin epitaxial GaAs films on Ge substrates with the aid of a 200 nm thin SiO2 mask layer. The selectively grown structures have lateral sizes ranging from 1 um width up to large areas of 1 by 1 mm2. The growth is fully selective, thanks to an optimized growth procedure, consisting of a 13 nm thin nucleation layer grown at high pressure, followed by low pressure growth of GaAs. This growth procedure inhibits the nucleation of GaAs on the mask area and is a good compromise between reduction of loading effects and inhibition of anti phase domain growth in the GaAs. Nevertheless, both microscopic and macroscopic loading effects can still be observed on x-section SEM images and profilometer measurements. X-ray diffraction and low temperature photoluminescence measurements demonstrate the good microscopic characteristics of the selectively grown GaAs.