On-Chip High-Voltage Sensors Based on Trap-Assisted 2DEG Channel Control

In this letter, we present a new device concept for compact high-voltage sensing with a high-impedance input port, consisting of an AlGaN/GaN high-electronmobility channel controlled by trapped carriers generated by a metallic electrode. The high voltage applied to the metallic electrode is determined by measuring the current of the biased high-electron-mobility channel. This approach replaces high voltage probing with low-current measurement and gives a complete isolation between the high-voltage node and the sensing point. Increasing the electrode-to-channel distance in the device leads to a larger measurable voltage range. The device sensitivity can be increased by applying a larger bias to the channel. The devices with extremely large input resistance of >100 GΩ in the sensitive region, along with 2-kV breakdown voltage, were fabricated in small dimensions of 50 μm × 50 μm. The high breakdown field of GaN (~3 MV/cm), as a widebandgap material, makes it possible to design and fabricate devices based on this topology for the future on and off-chip high-voltage sensing, providing extremely large input resistances that cannot be achieved by conventional methods.