Development of \u03b2-Ga2O3 layers growth on sapphire substrates employing modeling of precursors ratio in halide vapor phase epitaxy reactor

Galia Pozina,Chih-Wei Hsu,Natalia Abrikossova,Carl Hemmingsson,Mikhail A Kaliteevski

doi:10.1038/s41598-020-79154-9

Galia Pozina, Chih-Wei Hsu + Show 3 more

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https://doi.org/10.1038/s41598-020-79154-9

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Abstract

Gallium oxide is a promising semiconductor with great potential for efficient power electronics due to its ultra-wide band gap and high breakdown electric field. Optimization of halide vapor phase epitaxy growth of heteroepitaxial upbeta-Ga2O3 layers is demonstrated using a simulation model to predict the distribution of the ratio of gallium to oxygen precursors inside the reactor chamber. The best structural quality is obtained for layers grown at 825–850 °C and with a III/VI precursor ratio of 0.2. Although the structural and optical properties are similar, the surface morphology is more deteriorated for the upbeta-Ga2O3 layers grown on 5 degree off-axis sapphire substrates compared to on-axis samples even for optimized process parameters. Cathodoluminescence with a peak at 3.3 eV is typical for unintentionally doped n-type upbeta-Ga2O3 and shows the appearance of additional emissions in blue and green region at ~ 3.0, ~ 2.8, ~ 2.6 and ~ 2.4 eV, especially when the growth temperatures is lowered to 800–825 °C. Estimation of the band gap energy to ~ 4.65 eV from absorption indicates a high density of vacancy defects.

Highlights

Gallium oxide is a promising semiconductor with great potential for efficient power electronics due to its ultra-wide band gap and high breakdown electric field
Gallium oxide ( Ga2O3) is an ultra-wide band gap semiconductor gaining today much attention due to its high breakdown electric field, which is essential for modern high voltage, energy efficient high power electronics and optoelectronics1. Ga2O3 can be synthesized in several different phases ( α, β, ε, δ, γ, κ ) and even more polymorphs are predicted from first-principles c alculations[2]
We used Halide vapor phase epitaxy (HVPE) growth for producing thick GaN layers in vertical reactor[18,19], while here we exploit a horizontal chamber consisting of a quartz tube inside a furnace with three temperature zones

Summary

Introduction

Gallium oxide is a promising semiconductor with great potential for efficient power electronics due to its ultra-wide band gap and high breakdown electric field. Epitaxial growth is affected by many different process parameters such as the geometry of the chamber and gas inlet/outlet, distance to the sample holder, heating temperature and its gradient in the reactor, gas flows, precursors ratio, pressure, etc.

Results

Conclusion