# GaN metal-organic vapor phase epitaxy on Sc2O3/Si templates for group III-nitride monolithic integration to Si technology

## TL;DR

This paper explores growing high-quality GaN layers on silicon using a Sc2O3 buffer to improve integration with silicon technology.

## Contribution

A novel strain-engineering approach using AlxGa1-xN interlayers to produce smooth GaN layers on Sc2O3/Si templates is introduced.

## Key findings

- Switching growth atmosphere from nitrogen to hydrogen reduces cubic GaN formation and improves surface morphology.
- Prolonged nitridation improves GaN crystallinity and reduces defects.
- Strain-engineering with AlxGa1-xN interlayers produces crack-free GaN layers on silicon.

## Abstract

In this work, we present a detailed analysis of GaN layers up to 500 nm thick, directly grown on Sc2O3(111)/Si(111) templates using metal-organic vapor phase epitaxy. A range of measurement techniques, including X-ray diffraction, Raman spectroscopy, atomic force microscopy, cathodoluminescence, and scanning electron microscopy (SEM), were used to evaluate structural quality, strain/stress states, surface morphology, and dislocation densities. The micro-stripe formation was observed when the growth was conducted in a nitrogen atmosphere, with the stripes completely disappearing when the growth atmosphere was switched to hydrogen. The stripes were determined to be of a cubic GaN phase. The epitaxial relationships between the cubic GaN crystalline lattice and Sc2O3, Si, and hexagonal GaN were examined in detail. Continuous, c-axis-oriented, monocrystalline GaN layers on Sc2O3 can be achieved in both \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {N}_2$$\end{document} and \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {H}_2$$\end{document} atmospheres. Prolonged nitridation processes of up to 1200 s improved the smoothness and crystallinity of the GaN layers, significantly reducing the number of extended defects. Switching the growth atmosphere from \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {N}_2$$\end{document} to \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {H}_2$$\end{document} led to reduced dislocation densities, minimized cubic GaN formation, and improved the surface morphology of the GaN layers. Our analysis shows that due to the lattice and thermal mismatch between GaN and the Si substrate, the GaN layers experience tensile strain. To manage this strain, \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {Al}_x$$\end{document}
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\begin{document}$$\hbox {Ga}_{1-x}$$\end{document}N interlayers were inserted after 100 nm of GaN growth. This strain-engineering approach resulted in smooth, crack-free GaN epitaxial layers, demonstrating the potential for integrating GaN into silicon technology using a \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {Sc}_{{2}}$$\end{document}
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\begin{document}$$\hbox {O}_{{3}}$$\end{document}.