Dual-channel 2DEG micro-Hall effect sensor for extreme environments

We report a dual-channel two-dimensional electron gas (2DEG) micro-Hall sensor of AlN/GaN/AlN/GaN heterostructure for extreme environments. The fabricated Hall sensor shows a supply voltage-related sensitivity of ∼0.058 T−1 and a supply current-related sensitivity of ∼37.1 V A−1 T−1 at room temperature. It maintains a linear response from −193 to 407 °C in the range of magnetic fields of −0.25 to +0.25 T, with the bias range of 12 mA or 10 V. The temperature coefficient of sheet resistance is 1.1 Ω/°C, which reflects the usefulness in detecting temperature at the spatial location of high-power module. The measured Hall offset response time of ∼60 ns closely matches with the bias response of ∼63 ns, indicating that offset is in phase with the bias current. We also observed that, at low magnetic fields, the rise time is primarily influenced by offset voltage, whereas at higher fields, it is dominated by the slower response of the Hall signal. Furthermore, Hall signal phase shifts of 29.8° and 50.5° were observed at −60 and −240 mT, and 57.1° and 105° at +60 and +240 mT, respectively, and also provide an explanation for the observed correlation. This phase difference can be used to isolate the Hall signal from the Hall-offset with lock-in detection.