Ultrawide Band Gap \beta-Ga2O3 Nanomechanical Resonators with Spatially Visualized Multimode Motion

TL;DR

This paper demonstrates ultrawide band gap -Ga2O3 nanomechanical resonators with multimode motion visualization, revealing their mechanical properties and effects of thermal annealing, paving the way for advanced electronic and sensing devices.

Contribution

It introduces the experimental realization of -Ga2O3 nanomechanical resonators with multimode motion visualization and analyzes their mechanical properties and thermal treatment effects.

Findings

Achieved multimode nanoresonators up to 6th mode in high and very high frequency bands.

Thermal annealing improved resonance frequency by ~40% and Q factor by ~90%.

Measured Young's modulus of 261 GPa and anisotropic biaxial tension in -Ga2O3 nanostructures.

Abstract

Beta gallium oxide (\beta-Ga2O3) is an emerging ultrawide band gap (4.5 - 4.9 eV) semiconductor with attractive properties for future power electronics, optoelectronics, and sensors for detecting gases and ultraviolet radiation. \beta-Ga2O3 thin films made by various methods are being actively studied toward such devices. Here, we report on the experimental demonstration of single-crystal \beta-Ga2O3 nanomechanical resonators using \beta-Ga2O3 nanoflakes grown via low-pressure chemical vapor deposition (LPCVD). By investigating \beta-Ga2O3 circular drumhead structures, we demonstrate multimode nanoresonators up to the 6th mode in high and very high frequency (HF / VHF) bands, and also realize spatial mapping and visualization of the multimode motion. These measurements reveal a Young's modulus of E_Y = 261 GPa and anisotropic biaxial built-in tension of 37.5 MPa and 107.5 MPa. We find that thermal annealing can considerably improve the resonance characteristics, including ~40% upshift in frequency and ~90% enhancement in quality (Q) factor. This study lays a foundation for future exploration and development of mechanically coupled and tunable \beta-Ga2O3 electronic, optoelectronic, and physical sensing devices.