Temperature Dependence of the Resistance of AlGaN/GaN Heterostructures and Their Applications as Temperature Sensors

AlGaN/GaN heterostructures with a two-dimensional electron gas (2DEG) exhibit unique transport properties that could potentially be used for novel applications that are not related to conventional modulation-doped field effect transistor devices. Here, we describe the fabrication of high sensitivity temperature sensors exploiting temperature induced resistance changes of AlGaN/GaN-2DEG heterostructures. We observed a monotonous change in the resistance of the 2DEG from 3 to 1000 K. The temperature dependence of the resistance above 180 K fitted the Callender-Van Dusen equation. The sensitivity of the AlGaN/GaN temperature sensors was more than 2 times higher than conventional resistance temperature detectors near room temperature and 5 times higher at about 900 K. These new AlGaN/GaN temperature sensors may find niche applications in extreme environments, such as space exploration, as well as where high sensitivity is required over wide temperature ranges. (C) 2010 The Japan Society of Applied Physics