A porous GaN/MoO3 heterojunction for filter-free, ultra-narrowband ultraviolet photodetection

Abstract

Commonly, a narrowband photodetector that can detect specific wavelengths is obtained by integrating a broadband photodetector with an external optical filter. However, this integration significantly increases the structural complexity and cost, and reduces the sensitivity. Herein, we demonstrate a filter-free, ultra-narrowband, ultraviolet photodetector based on a porous GaN/MoO₃ heterojunction. Porous GaN with reduced defects and enhanced light trapping was fabricated by a facile photoelectrochemical etching method. The optimized porous GaN/MoO₃ photodetector shows visible-blind (peaked at 370 nm) and ultra-narrowband (FWHM <10 nm) ultraviolet photoresponse. Moreover, the photodetector exhibits a large light-to-dark current ratio (nearly 10⁵ at −3 V), along with a remarkable responsivity, external quantum efficiency, and detectivity of 187.5 mA W⁻¹, 62.8%, and 4.34 × 10¹² Jones, respectively. The highly-performing and narrowband response makes the porous GaN/MoO₃ ultraviolet photodetector promising for secure optical communication systems.