Disentangling the Role of the SnO Layer on the Pyro‐Phototronic Effect in ZnO‐Based Self‐Powered Photodetectors

Abstract

AbstractSelf‐powered photodetectors (PDs) have been recognized as one of the developing trends of next‐generation optoelectronic devices. Herein, it is shown that by introducing a thin layer of SnO film between the Si substrate and the ZnO film, the self‐powered photodetector Al/Si/SnO/ZnO/ITO exhibits a stable and uniform violet sensing ability with high photoresponsivity and fast response. The SnO layer introduces a built‐in electrostatic field to highly enhance the photocurrent by over 1000%. By analyzing energy diagrams of the p‐n junction, the underlying physical mechanism of the self‐powered violet PDs is carefully illustrated. A high photo‐responsivity (R) of 93 mA W−1 accompanied by a detectivity (D*) of 3.1 × 1010 Jones are observed under self‐driven conditions, when the device is exposed to 405 nm excitation laser wavelength, with a laser power density of 36 mW cm−2 and at a chopper frequency of 400 Hz. The Si/SnO/ZnO/ITO device shows an enhancement of 3067% in responsivity when compared to the Al/Si/ZnO/ITO. The photodetector holds an ultra‐fast response of ≈ 2 µs, which is among the best self‐powered photodetectors reported in the literature based on ZnO.