Depleting and Hot-Electron Injection Effect: Mechanism of Boosting the Photo- Respond Speed for ZnO Nanorods MSM Photodetectors by Sandwiching Ag Nanoparticles in AZO

Abstract ZnO is one of the most used materials in optoelectronic devices, however, owing to the adsorption of oxygen, ZnO photodetectors (PDs) usually possess slow response in photo detection. In this work, we present the photodetectors of ZnO NRs based on sandwiched AZO/Ag NPs/AZO seed layer. The PDs with Ag NPs embedded showed much fast response speed and the response time required is 0.61 s, which is one order lower under polychromatic light excitation. Meanwhile, the on/off ratio was observed as 750.92 with the responsivity of 66.58 mA/W under Xenon Lamp. The inducement of fast response can be attributed to the cooperation between interfacial depleting and plasmon hot electron injection that triggers “deposition and withdraw” mechanism for the carriers. The mechanism was systematically explored with the characterization under monochromatic excitation including 375, 430 and 520 nm. The sandwich design offers an approach for plasmon NPs of being utilized in semiconductor photodetectors.