Research On Carrier Behavior And Photoelectric Performance Of Cu₂O/ZnO Heterojunction

The third-generation semiconductor material ZnO has become one of the hotspots in the optoelectronic materials due to its simple preparation process,non-toxic and harmless nature,and high electron mobility.However,the wide band gap of ZnO（3.37 e V）limits its detection range to the ultraviolet region,extending its excellent optoelectronic properties to the visible light region has been the research focus.In recent years,heterojunctions formed by compounding wide-bandgap ZnO with narrow-bandgap semiconductor material cuprous oxide（Cu₂O）has been proven to be an effective way to enhance the visible light response performance of ZnO-based photodetectors.Currently,most of the research on Cu₂O/ZnO heterojunction photodetectors focus on improving the photoelectric performance of the device by doping,interface modification,etc.,while the physical mechanism of photoelectric conversion remains ambiguous,especially the explanation of the carrier behavior properties during the photodetection process still needs to be uncovered.To address the above issues,in this thesis,the ordered arrays of ZnO nanorods（NRs）are synthesized by hydrothermal method without introducing other functional layer materials.The magnetron sputtering method realizes the controllable construction of high-performance Cu₂O/ZnO heterojunction photodetectors,and further explains the relationship between the evolution of carrier behavior and the photoelectric conversion properties of the device from a microscopic perspective.Finally,the device was successfully applied in optical communication.The main contents of this work are as follows:（1）To address the problem of the photoresponse of the ZnO-based photodetector being limited to the ultraviolet region,a Cu₂O/ZnO heterojunction photodetector was constructed by compounding with the P-type narrow bandgap material Cu₂O,extending the device’s detection range to the visible light region.Based on this structure,the photoelectric conversion mechanism of the p-n junction photodetector was further explored under zero bias voltage,resulting in zero bias self-driven detection under visible light with a high detectivity of1.36×10¹² Jones.（2）To address the problem of unclear photocarrier behavior in heterojunction devices,the relationship between carrier generation,separation,transport and recombination in Cu₂O/ZnO heterojunction photodetectors was investigated by adjusting the structure of the functional layer.The fabricated device exhibits high photoelectric responsivity(45.74m A·W^-1)and fast response speed（11.4 ms）under zero bias voltage.（3）Based on the piezo-phototronic effect,the stress was applied to modify the interface structure between Cu₂O and ZnO,and the photocarrier behavior in coupled force field was further elucidated.With the force of 45 N,the photocurrent of the device changed by 12.8%,which verifies the effectiveness of the force field on the performance modulation of ZnO-based photodetectors.Furthermore,the prepared Cu₂O/ZnO heterojunction photodetector could accurately translate the code,showing its good application prospect in optical communication.