Ultrawide Band Gap β‑Ga2O3 Nanomechanical Resonators with Spatially Visualized Multimode Motion

• Published in: ACS applied materials & interfaces Vol. 9; no. 49; pp. 43090 - 43097
• Main Authors: Zheng, Xu-Qian, Lee, Jaesung, Rafique, Subrina, Han, Lu, Zorman, Christian A, Zhao, Hongping, Feng, Philip X.-L
• Format: Journal Article
• Language: English
• Published: American Chemical Society 13.12.2017
• Subjects: annealing; electronics; gallium; materials science; modulus of elasticity; semiconductors; ultraviolet radiation; vapors; Young’s modulus; nanoelectromechanical systems (NEMS); mode shape; beta gallium oxide (β-Ga2O3); annealing; spatial mapping; resonators
• ISSN: 1944-8244; 1944-8252; 1944-8252
• DOI: 10.1021/acsami.7b13930

Beta gallium oxide (β-Ga2O3) is an emerging ultrawide band gap (4.5 eV–4.9 eV) semiconductor with attractive properties for future power electronics, optoelectronics, and sensors for detecting gases and ultraviolet radiation. β-Ga2O3 thin films made by various methods are being actively studied toward such devices. Here, we report on the experimental demonstration of single-crystal β-Ga2O3 nanomechanical resonators using β-Ga2O3 nanoflakes grown via low-pressure chemical vapor deposition (LPCVD). By investigating β-Ga2O3 circular drumhead structures, we demonstrate multimode nanoresonators up to the sixth 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 β-Ga2O3 electronic, optoelectronic, and physical sensing devices.