Ferroelectricity-induced performance enhancement of V-doped ZnO/Si photodetector by direct energy band modulation

Ferroelectric materials have exhibited immense promise for the control of optoelectronic processes in emerging devices. However, the utilization of ferroelectric materials to directly modulate the energy band at the junction interface has rarely been investigated. Here, a ferroelectric V-doped ZnO nanosheets/p-Si heterojunction photodetector (VZnO/Si PD) has been prepared, and the effect of ferroelectricity on the photoresponse performance of the VZnO/Si PD is studied deeply. Due to the existence of aligned ferroelectric spontaneous polarization charges under applied electrical field, the junction interface energy band can be modulated directly and effectively, which greatly improves the generation, separation and transportation efficiency of photogenerated electron-hole pairs. In contrast with the non-ferroelectric ZnO/Si PD, the VZnO/Si PD has a large enhancement in photoresponse performance with a twelve-fold increase in the photoresponsivity (R) under +1 V bias, accompanied by fast response speed in a broad spectral range. Interestingly, even under the -1 V bias voltage, the reverse ferroelectric polarizations also can improve the photoresponse behavior. These results prove the feasibility of direct modulation on energy band structure at the junction interface by ferroelectricity, which provides a new perspective for energy band engineering.