Gallium Arsenide‐Based Active Antennas for Optical Communication Photodetection with Robustness to Voltage and Temperature

Although gallium arsenide (GaAs) is one of the most commonly used semiconductor substrate materials, its intrinsic bandgap of 1.42 eV hinders the use of GaAs photodetectors for optical communication. In this study, hot-electron-based GaAs active antenna devices are demonstrated, displaying photoresponses well below the bandgap at the telecommunication wavelengths. Using a deep-trench/thin metal (DTTM) active antenna, a metallic plasmonic structure, high photoresponsivities are achieved under zero bias at wavelengths of 1310 and 1550 nm. Even though the resistance of the semi-insulating GaAs substrate is approximately 10(6) times larger than that of the n-type silicon (Si) substrate, the photoresponsivities are commensurate with most previously reported hot-electron n-Si-based photodetectors operating at communication wavelengths. Furthermore, the devices can be operated under a reverse-biased voltage with significant enhancements in the photoresponsivities; the highest photoresponsivity (19.96 mA W-1 at 1310 nm) is greater than those reported in all previous studies. Moreover, these GaAs-based devices are sufficiently robust to be operated over a wide range of operating temperatures (from -193 to +200 degrees C) while displaying a relatively large bandgap, low dark leakage currents, and high electron mobilities at low temperature. Because these devices can operate at high and low temperatures and at large voltage biases, they are suitable for use under harsh environmental conditions.