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

Abstract

In 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.