Temperature, Sensitivity, and Frequency Response of AlN/GaN Heterostructure Micro-Hall Effect Sensor

We report for the first time on an aluminum nitride/gallium nitride (AlN/GaN) heterostructure as a microscale Hall effect sensor for current sensing applications in extreme environments. The AlN/GaN devices demonstrated high signal linearity as a function of the magnetic field across a temperature range from <tex-math notation="LaTeX">$-$</tex-math> 193 <tex-math notation="LaTeX">∘</tex-math> C to 407 <tex-math notation="LaTeX">∘</tex-math> C. The measured room temperature (RT) supply voltage-related sensitivity ( <tex-math notation="LaTeX">Sₛᵥᵣₛ)</tex-math> and supply current-related sensitivity ( <tex-math notation="LaTeX">Sscrs)</tex-math> are 0.055 T <tex-math notation="LaTeX">⁻¹</tex-math> and 32 VA <tex-math notation="LaTeX">⁻¹</tex-math> T <tex-math notation="LaTeX">⁻¹</tex-math> , respectively. The supply power-related sensitivity ( <tex-math notation="LaTeX">Sₛₚᵣₛ)</tex-math> is 1.4 VW <tex-math notation="LaTeX">⁻¹</tex-math> T <tex-math notation="LaTeX">⁻¹</tex-math> above 40-mW input bias, which is higher than that of the Al <tex-math notation="LaTeX">0.2</tex-math> Ga <tex-math notation="LaTeX">0.8</tex-math> N/GaN device. The designed AlN/GaN micro-Hall sensor is further determined to have a lower power consumption and higher temperature sensitivity than equivalent Al <tex-math notation="LaTeX">0.2</tex-math> Ga <tex-math notation="LaTeX">0.8</tex-math> N/GaN Hall devices. When operated in an ac bias mode, the rise time of the Hall sensor was found to be 102 ns, corresponding to a frequency bandwidth of 9.8 MHz. We also observed a phase shift between an applied magnetic field and the Hall sensor signal, which can potentially be helpful to monitor ac line currents.