Abstract
Most heterojunction photodetectors (PDs) can detect single-band, dual-band, or even multi-band light. However, the ability to adjust the spectral response band of the PD remains a challenge. This study presents a self-powered PD based on a ZnO/Cu2O heterojunction that overcomes this limitation. Adjustable and selective detection bands were achieved within a single device by controlling the direction of the incident light. Under zero bias conditions, the PD exhibits a response exclusively in the 500–750 nm region when the light is incident from the ZnO side, with a responsivity of 1.27 mA W−1. Conversely, when the light is incident from the Cu2O side, responsivities of 10.63 and 52.42 mA W−1 are achieved in the 275–750 nm region. Remarkably, the ZnO/Cu2O PD enables tunable detection of the response region depending on the incident light direction. The dual-band response is attributed to the differential distribution of the width of the depletion layer and the built-in electric field. This study offers valuable insights into the potential applications of PDs with spectral selectivity in optical communication, sensing, and intelligent optoelectronic devices.
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