[11a-N101-1~9] 15.4 III-V-group nitride crystals

11:15 AM - 11:30 AM JST(2:15 AM - 2:30 AM UTC)

[11a-N101-9] High-Q GaN MEMS resonators on sapphire enabled by a lattice-matched Al_xIn_1-xN sacrificial layer

〇Masataka Imura¹, Takanobu Hiroto¹, Takayoshi Oshima¹, Takaaki Mano¹, Wen Zhao¹, Meiyong Liao¹, Yuri Itokazu², Masafumi Jo³, Tateki Mori⁴, Ya Zhang⁴ (1.NIMS, 2.BeamTech., 3.RIKEN, 4.TUAT)

Keywords:

GaN MEMS resonator,AlInN sacrificial layer,Cantilever resonator

Gallium nitride (GaN) is an attractive material for microelectromechanical systems (MEMS) resonators because of its wide bandgap, high Young’s modulus, and excellent chemical stability. Realization of suspended structures is essential for high-Q operation, and the development of suitable sacrificial layers remains a key challenge. Lattice-matched Al_xIn_1–xN is a promising sacrificial-layer material for GaN MEMS; however, growth of thick, high-quality layers while maintaining lattice matching is difficult, and its applicability to MEMS resonators has not been fully investigated.In this work, GaN/Al_xIn_1–xN/GaN heterostructures incorporating an approximately 500-nm-thick lattice-matched Al_xIn_1–xN sacrificial layer were grown on sapphire substrates by metal-organic vapor phase epitaxy (MOVPE). Suspended GaN MEMS resonators were fabricated using ICP-RIE dry etching followed by selective wet etching in heated nitric acid. X-ray diffraction reciprocal-space mapping and cross-sectional transmission electron microscopy confirmed lattice matching and high crystal quality of the multilayer structure.Selective removal of the Al_xIn_1–xN layer successfully formed suspended GaN cantilever resonators. Resonance measurements using laser Doppler vibrometry showed a clear resonance peak with a quality factor of approximately 26,600. This value is higher than that previously reported for GaN cantilevers fabricated on bulk GaN substrates using an In_xGa_1–xN sacrificial layer and electrochemical etching. These results demonstrate the effectiveness of thick lattice-matched Al_xIn_1–xN sacrificial layers for realizing high-Q GaN MEMS resonators on sapphire substrates.