Surface Plasmon‐Enhanced High‐Performance ZnO/Ni/ZnO Ultraviolet Photodetectors

The surface plasmon effect of Ni thickness on the optical and electrical properties of ZnO/Ni/ZnO multilayer structure (MS) ultraviolet photodetectors (PDs) is investigated. In general, ZnO/Ni/ZnO MS can be used as a transparent conductive oxide. As the thickness of the Ni thin interlayer increases from 0 to 8 nm, the optical transmittance of the ZnO/Ni/ZnO MS‐PDs decreases from 90.9% to 54.4%. The optical absorptions of the Ni/ZnO and ZnO/Ni/ZnO MS films increase with a 2.0 nm‐thick Ni film. In addition, despite depositing a Ni film on ZnO, the maximum photoluminescence (PL) intensity is obtained from the 2.0 nm‐thick Ni on the ZnO film. However, the optical absorption and PL band‐edge emission of ZnO/Ni/ZnO MS‐PDs decrease gradually with increasing Ni film thickness (>2.0 nm). Thus, this optical improvement of ZnO/Ni/ZnO can be caused by the surface plasmon effect, which leads to an increase in the number of photogenerated carriers in ZnO/Ni/ZnO MS‐PDs. Therefore, the higher photoresponsivity (19.5 mA W −1 ) and external quantum efficiency (6.5%) of the ZnO/Ni/ZnO MS‐PDs are achieved with a 2.0 nm‐thick Ni interlayer compared with ZnO single‐layer PDs.