Temperature enhanced responsivity and speed in an AlGaN/GaN metal-heterostructure-metal photodetector

An AlGaN/GaN metal-heterostructure-metal (MHM) ultraviolet (UV) photodetector employing lateral Schottky contacts was fabricated and characterized at different temperatures. As the temperature increased from 25 to 250 °C, the photoresponsivity of the MHM photodetector increased 3.5 times. This was attributed to the spontaneous-polarization-induced spatial separation of the photogenerated electrons and holes and the increased optical absorption at higher temperatures. Meanwhile, the decay time constant of the photocurrent became approximately three orders of magnitude smaller. With the enhanced photoresponsivity and the decreased response time constant, kilohertz optical switching of the MHM photodetector was recorded at 250 °C. The AlGaN/GaN MHM photodetector, sharing the same GaN-on-Si electronics platform, provides an applicable candidate for an all-GaN integrated UV sensing and amplifying system for high-temperature applications.