Ultrasensitive self‐powered UV PDs via depolarization and heterojunction fields jointly enhanced carriers separation

Abstract

AbstractIn current semiconductor‐based self‐powered ultraviolet (UV) photodetectors (PDs), because the built‐in electric field only exits in the space‐charge region of p‐n junction or Schottky junction interfaces, the photo‐generated carriers can't be efficiently separated and thus the photoelectric response is low. To solve this issue, in this work, we design and fabricate new‐type Pb,La(Zr,Ti)O3 ferroelectrics/TiO2 semiconductors heterojunction self‐powered UV photodetectors. The results indicate that by introducing Pb,La(Zr,Ti)O3 ferroelectric layers, the photocurrent of the PDs is greatly improved and at a negative poling electric voltage, the device exhibits excellent self‐powered UV photoelectric properties with a large responsivity of 21 mA/W, high specific detectivity of 2.4 × 1011 Jones, and fast response speed (rise time of 2.4 ms, decay time of 3.2 ms). These values are far superior to those of all recently reported self‐powered UV PDs and their huge improvement is primarily because the depolarization field caused by the high remnant polarization of Pb,La(Zr,Ti)O3 and the built‐in electric field resulting from the heterojunction interfaces of the Pb,La(Zr,Ti)O3 and the TiO2 thin films jointly enhance the separation efficiency of photo‐generated electrons and holes. Besides, the heterojunction PDs also show good weak UV light detection ability. This work opens new avenue for designing and fabricating next‐generation self‐powered UV PDs by a simple, low‐cost, and easy to mass‐produce way.