# Polycrystalline κ-Ga2O3 on Si(100) substrates with GZO buffer layers

## TL;DR

Researchers successfully grew a piezoelectric semiconductor on silicon using a buffer layer, which could lead to better radio-frequency devices.

## Contribution

A method for growing polycrystalline κ-Ga2O3 on Si(100) substrates using GZO buffer layers is demonstrated.

## Key findings

- Polycrystalline κ-Ga2O3 films exhibit a c-axis oriented structure with random in-plane orientations.
- A ZnGa2O4 intermediate layer forms at the κ-Ga2O3/GZO interface, aiding phase stabilization.

## Abstract

Kappa-phase gallium oxide (κ-Ga2O3) is an emerging piezoelectric semiconductor with potential applications in radio-frequency devices. However, heteroepitaxial growth of κ-Ga2O3 on silicon substrates remains challenging owing to large lattice mismatch and interfacial oxidation. This study demonstrates the growth of polycrystalline κ-Ga2O3 thin films deposited by mist chemical vapor deposition (mist CVD) on Si(100) substrates using Ga-doped ZnO (GZO) buffer layers. Structural characterization via X-ray diffraction, scanning electron microscopy, and transmission electron microscopy reveals that κ-Ga2O3 films exhibit a c-axis oriented polycrystalline structure with random in-plane orientations, which yields isotropic properties that are advantageous for device applications. A ZnGa2O4 intermediate layer is identified at the κ-Ga2O3/GZO interface, which plays a critical role in phase stabilization. These findings indicate that polycrystalline κ-Ga2O3 on Si substrates represents a promising platform for piezoelectric semiconductor devices.

Polycrystalline κ-Ga2O3 was successfully deposited on a Si substrate using a GZO buffer layer. Furthermore, it was revealed that a ZnGa2O4 transition layer forms during the growth process.