Dual-Channel 2DEG Micro-Hall Effect Sensor for Extreme Environments

We report, for the first time, a dual-channel 2DEG micro-Hall sensor of AlN\/GaN\/AlN\/GaN heterostructure, designed for extreme environments. Fabricated Hall sensor shows a supply voltage-related sensitivity of ~0.058 T-1 and a supply current-related sensitivity of ~37.1 VA-1T-1 at room temperature. It maintains a linear response from \u2013193 to 407\u00b0C in the magnetic fields ranges of \u20130.25 to +0.25 T, with the bias range of 12 mA or 10 V. The temperature coefficient of sheet resistance is 1.1 \u03a9\/\u00b0C, which reflects the usefulness in detecting temperature at the spatial location of high-power modules for multifunctional sensing. The measured Hall offset response time of ~60 ns closely matches with the bias transient time of ~63 ns, this result indicates that offest 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, rise time dominated by the slower response of the Hall signal. Further, Hall signal phase shifts of 29.8\u00b0 and 50.5\u00b0 were observed at \u201360 and \u2013240 mT, and 57.1\u00b0 and 105\u00b0 at +60 and +240 mT, correspondingly, and also provide an explanation for the observed correlation. This phase difference can be used to isolate the Hall signal with lock-in detection