Facile Geometry Engineering of Deep Ultraviolet Micro‐Scale Light Emitting and Detecting Diodes for High‐Speed Free‐Space Optical Communication

Abstract

Dual‐functional micro‐diodes are attractive for compact multifunctional sensing and free‐space optical communication, yet performance in ultrasmall geometries is limited by poor photon extraction and suboptimal optical coupling. Here, we report a trench‐aspect‐ratio reconfiguration strategy in the fabrication of triangular‐shape multiple‐quantum‐well micro‐diodes for both device‐ and system‐level integrated photonics. Two diodes with mesa area of 2500 µm 2 are fabricated on the same wafer, including a regular triangle (RT‐diode) and a narrow triangle (NT‐diode). Despite nearly unchanged junction characteristics, the NT‐diode shows improved performance in both emission and detection. In emitting mode, it delivers a much‐improved light output power while enhancing transverse‐mode‐associated emission, and a slightly lower device temperature after a fixed drive interval. In detecting mode under 260 nm illumination, responsivity is boosted from 163 to 191 mA/W, while preserving nanosecond‐scale response dynamics. Optical modeling in both emission and detection modes reveals a common geometry‐mediated performance enhancement and its underlying mechanism. Strikingly, the NT‐diode achieves a benchmarking bandwidth of ∼480 MHz with a high data rate of 2.688 Gbps in a solar‐blind optical communication scheme. A proof‐of‐concept bidirectional free‐space communication further validates the compact transceiver operation of the proposed triangular micro‐diodes for next‐generation integrated photonics and optical communication.