Facile Enhancement of Optical Sensitivity in GaN Ultraviolet Photodetectors by Using In-Situ Plano-Convex Polymer Lens

The facile enhancement of the optical photocurrent in gallium nitride (GaN) ultraviolet (UV) photodetectors was realized by applying an in-situ curing technique to polymer lenses on a GaN surface. To fabricate plano-convex polymer lenses that focus incident UV light, a prepolymer was dropped directly onto the GaN surface and cured at room temperature to induce UV light refraction. When the incident light passed through the polymer lens, the light concentrated on the sensing area of the GaN photodetector, thus generating more photocurrent than GaN photodetectors without the lens. Consequently, photodetectors fabricated with the plano-convex polymer lenses exhibited higher optical sensitivity (up to ~18.16% increase in photocurrent at room temperature) than those fabricated without polymer lenses. This study supports the use of direct and in-situ curing of polymer lenses on GaN surfaces for the facile and reliable enhancement of optical sensitivity of various GaN-based optoelectronics.