On-Chip Integrated High-Sensitivity Temperature Sensor Based on p-GaN/AlGaN/GaN Heterostructure

An on-chip integrated temperature sensor based on a
${p}$
-GaN/AlGaN/GaN heterostructure is demonstrated. The sensor consists of a two-dimensional-electron-gas (2DEG) resistor and a Schottky-metal/
${p}$
-GaN/AlGaN/GaN (PiN) diode, which are connected in series and fabricated on one heterostructure. The conduction current of the 2DEG resistor features a negative temperature-dependence, while that in the PiN diode features a positive dependence due to its bipolar-electron/hole-injection nature. When they are properly biased, the divided voltage between the two units is redistributed with elevated temperatures. At a supply voltage of 10 V, the sensor presents a maximum and recorded sensitivity of 19.7 mV/°C in a temperature range from 25 °C to 300 °C due to the opposing temperature dependence of the two units. The fabrication process and the heterostructure of the temperature sensor are fully compatible with high-electron-mobility transistors, enabling in situ temperature detection and protection with enhanced accuracy and sensitivity.