Ultrafast miniaturized GaN-based optoelectronic proximity sensor

In this work, a novel ultrafast optoelectronic proximity sensor based on a submillimeter-sized GaN monolithic chip is presented. Fabricated through wafer-scale microfabrication processes, the on-chip units adopting identical In Ga N/Ga N diode structures can function as emitters and receivers. The optoelectronic properties of the on-chip units are thoroughly investigated, and the ability of the receivers to respond to changes in light intensity from the emitter is verified, revealing that the sensor is suitable for operation in reflection mode. Through a series of dynamic measurements, the sensor is highly sensitive to object movement at subcentimeter distances with high repeatability. The sensor exhibits ultrafast microsecond response, and its real-time monitoring capability is also demonstrated by applying it to detect slight motions of moving objects at different frequencies, including the human heart rate, the vibration of the rotary pump, the oscillation of the speaker diaphragm, and the speed of the rotating disk. The compact and elegant integration scheme presented herein opens a new avenue for realizing a chip-scale proximity sensing device, making it a promising candidate for widespread practical applications.