$\beta$ -Ga2O3 NEMS Oscillator for Real-Time Middle Ultraviolet (MUV) Light Detection

built by employing a vibrating β-Ga
₂
O
₃
nanoresonator as the frequency reference for real-time middle ultraviolet (MUV) light detection. We fabricate suspended β-Ga
₂
O
₃
nanodevices through synthesis of β-Ga
₂
O
₃
nanoflakes using low-pressure chemical vapor deposition and dry transfer of nanoflakes on microtrenches. Open-loop tests reveal a resonance of the β-Ga
₂
O
₃
device at ~30 MHz. A closed-loop oscillator is then realized by using a combined optical-electrical feedback circuitry, to perform real-time resonant sensing of MUV irradiation. The oscillator exposed to cyclic MUV irradiation exhibits resonant frequency downshifts, with a measured responsivity of R ≈ -3.1 Hz/pW and a minimum detectable power of δP
_min
≈ 0.53 nW for MUV detection.