Suspended p–n Junction InGaN/GaN Multiple-Quantum-Well Device With Selectable Functionality

We demonstrate optoelectronic devices implemented on suspended p-n junction InGaN/GaN multiple quantum wells (MQWs) for the further monolithic integration of an optical source, a waveguide, and a photodetector on the same GaN-on-silicon wafer. The fabricated suspended membrane device exhibits selectable functionalities either for efficient light-emitting diodes (LEDs) or sensitive photodetectors. Typical current-voltage (I-V) characteristics are obtained for the device operated under the LED mode, and the emitted light intensity is effectively modulated by the applied voltage. Lateral in-plane propagation of emitted light in a suspended membrane is experimentally presented. The simulation results show that the thickness-dependent optical performance can be tuned by back wafer thinning for epitaxial films. The device operated under the photodetector mode exhibits a static photocurrent on-off ratio η_s of 2.25 × 10⁵ at a 1-V bias voltage with the illumination power of 690 μW and the wavelength of 450 nm. The photocurrent also shows a rectangular pulse response of the same duration as a 1-s rectangular illumination pulse at a 0-V bias voltage with the illumination power of 1 mW. The temporal photocurrent on-off ratio η_t is around 1.01 × 10⁵. This paper opens a promising way to realize the monolithic integration of a LED, a waveguide, and a photodetector on a GaN-on-silicon platform.