| AVS 63rd International Symposium & Exhibition | |
| MEMS and NEMS | Thursday Sessions |
| Session MN+2D+NS-ThA |
| Session: | Focused Session on Atomic Layer Nanomechanics and 2D MEMS |
| Presenter: | Xu-Qian Zheng, Case Western Reserve University |
| Authors: | X.-Q. Zheng, Case Western Reserve University S. Rafique, Case Western Reserve University J. Lee, Case Western Reserve University L. Han, Case Western Reserve University C.A. Zorman, Case Western Reserve University H. Zhao, Case Western Reserve University P.X.-L. Feng, Case Western Reserve University |
| Correspondent: | Click to Email |
Among wide bandgap oxide semiconductors, β-Ga2O3 has recently been emerging as a promising candidate for future high-power electronics. Thanks to its direct wide bandgap, Eg≈4.9eV [1,2], power devices made of β-Ga2O3 may provide higher breakdown voltage even than that in high-power devices based on mainstream 4H-SiC and GaN materials. In addition to its excellent chemical and thermal stability [1, 2], β-Ga2O3 also possesses excellent mechanical properties (Young’s modulus, EY≈300GPa) [3], providing opportunities for creating next generation nano- and micro-electromechanical systems (NEMS and MEMS) which can be suited for operations in harsh and extreme environments.
In this work, we describe the construction of β-Ga2O3 nanosheets and their suspended structures, toward the first demonstration of vibrating β-Ga2O3 drumhead nanomechanical resonators. The nanomaterials were synthesized on 3C-SiC film covered Si substrate using a growth temperature of 950°C for 1.5hrs. No metal catalyst was used for the synthesis of the nanomaterials. The nanosheets have a width of ~2-7μm and thickness of ~20-140nm. The crystal structure and the morphology of the nanosheets were investigated by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). From high resolution FESEM image, it was confirmed that the nanosheets originated from the sidewall of the nanorods. The selected area electron diffraction pattern (SAED) taken along the [10-1] zone axis reveals that the synthesized nanosheets are single crystalline β-Ga2O3. We investigate the elastic properties and resonant characteristics of such devices, by measuring flexural-mode resonances using ultrasensitive laser interferometry. We fabricate circular drumhead β-Ga2O3 resonators with a diameter of ~3μm using a dry transfer technique. Then, by measuring undriven thermomechanical noise spectra of β-Ga2O3 resonators, we observe the resonance characteristics of such resonators at 37MHz to 66MHz in high frequency (HF) range with quality (Q) factors ranging 100 to 420. In addition, we observe static mechanical behaviors of β-Ga2O3. We perform nano-indentation on these drumhead structures using AFM tips to further study the elastic modulus of β-Ga2O3. By combining measured elastic properties from resonances and nano-indentation, this study provides quantitative understanding of mechanical properties of β-Ga2O3, and paves the way for future nanomechanical devices engineering based on this new crystal.
[1] S. Rafique, et al., Phys. Status Solidi (a)213, 1002-1009 (2016).
[2] S. Rafique, et al., Cryst. Growth Des.16, 511-517 (2016).
[3] M.-F. Yu, et al., IEEE Sensors J.5, 20-25 (2005).
[4] R. Yang, et al., J. Vac. Sci. & Tech. B 32, 061203 (2014).