Stable GaN nanoscale air channel array with ultralow-operated voltage and enhanced output current

III-nitride semiconductors, such as GaN, with many favorable material properties provide significant insight for nanoscale air channel devices to achieve high power and fast response even in harsh environments. In this Letter, a GaN-based nanoscale air channel arrays (NACAs) fabricated by low-cost and IC-compatible manufacturing technologies are proposed to improve the electrical performance. Without increasing the size, the vertical 4 × 4 GaN NACA with a 50 nm air channel exhibits an ultralow turn-on voltage of 0.32 V and a record output current of 70.2 mA at 10 V in air. The operating mechanisms of this typical device under low and high bias voltage have been explored. In addition, the device displays excellent emission stability as evidenced by its performance during a cycle test of 300 cycles and long-term testing. Moreover, the device presents high-speed and rapid switching characteristics with a repeatable response time of less than 50 ns. Therefore, this study paves the way for the miniaturization and integration of nanoscale vacuum electronic devices in the future.