Oxygen Plasma Surface Activation of Electron‐Depleted ZnO Nanoparticle Films for Performance‐Enhanced Ultraviolet Photodetectors

Abstract

Zinc oxide (ZnO) nanoparticles (NPs) with uniform particle radius comparable to the desired Debye length provide a low‐cost and a scalable scheme to achieve optimized electron depletion effect, which is the key to high performance ultraviolet (UV) photodetection. Here, a simple and improved sol–gel method for in situ synthesis of highly crystalline constituent ZnO‐NP mesoporous thin films is reported. In combination with optimal oxygen plasma treatment to activate the ZnO‐NP surface, the UV‐detection performance is enhanced remarkably with a reduced dark current by one order of magnitude and an increased UV detectivity by over 300%. Moreover, such UV photodetectors exhibit extraordinary performance with high responsivity of up to 0.8 A W−1V−1 at 340 nm UV power of 0.003 mW cm−2, detectivity of 1.4 × 1011 Jones, and rise/decay time of 3.4 s/5.0 s. These results illustrate that the sol–gel ZnO‐NP films provide a promising template for high‐performance UV detectors to take full advantages of the electron depletion effect.