Photoenhanced Field-Emission Nanoscale Air Channel Devices with High Temperature Tolerance for On-Chip Terahertz Generation.

Abstract

Nanoscale air channel devices (NACDs), characterized by scattering-free ballistic electron transport in a quasi-vacuum channel, provide a transformative platform for vacuum electronics and nanoelectronics. However, enabling NACDs for high-frequency operation is still a great challenge due to the low field-emission current and high impedance. Herein, photoenhanced NACDs are demonstrated as high-temperature-resistant photomixers capable of generating coherent terahertz (THz) signals from 120 to 260 GHz, offering the successful experimental demonstration of NACDs operating beyond 100 GHz. Vertical configuration NACDs with InP/InGaAs heterojunction photocathodes and 50 nm in-plane nanoscale air channels are designed and fabricated using a wafer-scale manufacturing process. The field-emission currents show an impressive 375-fold increase with low-power 1550 nm continuous wave (CW) laser irradiation. A high internal quantum efficiency of up to 1600% is achieved by exploiting the carrier multiplication effect within the heterojunction photocathodes. Furthermore, NACDs exhibit highly stable field-emission currents even at temperatures as high as 250 °C, breaking through the confines of traditional narrow-gap semiconductor photoelectric devices. These results establish NACDs as dual-functional platforms for both infrared detectors and on-chip THz generators operating at high temperatures, demonstrating their potential for high-speed optical communications, THz wireless communications, and 6G networks.