High Performance GaN-on-Si Voltage Sensors

Voltage sensors are highly important in power control systems for high efficiency and high reliability. In this work, we present miniaturized GaN-on-Si voltage sensors based on a back-gate topology: high-voltage signals ( ${V}_{\text {IN}}{)}$ applied on the substrate, and low-voltage ( ${V}_{\text {OUT}}{)}$ or low-current ( ${I}_{\text {OUT}}{)}$ output signals determined from the varying resistance of the two-dimensional electron gas (2DEG) at the device channel. The device presented high sensitivity of 5.97 $\pm ~0.16~\mu \text{S}$ , high input resistance ( ${R}_{\text {IN}}{)}$ up to 1.3 $\text{T}\Omega $ , and a low input capacitance of 1.6 nF/cm2. Excellent linearity and repeatability were demonstrated in both static and dynamic tests despite the trapping effects caused by carbon doping, thanks to an increased buffer thickness ( ${T}_{\text {BUF}}{)}$ . The rise and fall times ( ${t}_{\text {R}}$ and ${t}_{\text {F}}{)}$ are as short as 3.8 ± 0.22 and 3.2 $\pm ~0.13~\mu \text{s}$ , respectively, resulting in a large 3 dB bandwidth up to 180 kHz. In addition, the bipolar voltage sensing with high sensitivity and high linearity is also presented based on the p-GaN cap topology. The excellent performance and small footprint of the device, in addition to the low cost of the GaN-on-Si platform, render itself a promising candidate for future compact on-site DC voltage sensing applications.