GaN/AlN Heterostrucutre Micromechanical Self-Sustained Oscillator for Middle Ultraviolet (MUV) Light Detection

We report on the first experimental demonstration of micromechanical feedback oscillators based on vibrating gallium nitride/aluminum nitride (GaN/AlN) heterostructure doubly-clamped string resonators (~0.4-4 MHz) for real-time detection of middle ultraviolet (MUV) light. By exploiting the wide bandgap GaN/AlN hetero-structure and an optical-electrical feedback mechanism, the GaN/AlN string resonator-referenced oscillator exhibits frequency redshifts due to strong UV light absorption, with a measured responsivity of \mathfrakR=-24 Hz/nW and a minimum detectable power of δPmin=6.7 nW. Such GaN/AlN heterostructure micromechanical feedback oscillators, together with the appealing GaN/AlN electromechanical and optical properties, hold promise for real-time UV photon sensing and radiation effects studies.