We report on the appearance of a strong persistent photoconductivity (PPC) and conductor-like behaviour in zinc tin oxide (ZTO) thinfilm phototransistors. The active ZTO channel layer was prepared by remote plasma reactive sputtering and possesses an amorphous structure. Under sub-bandgap excitation of ZTO with UV light, the photocurrent reaches as high as ~ 10⁻⁴ A (a photo-to-dark current ratio of ~ 10⁷) and remains close to this high value after switching off the light. During this time, the ZTO TFT exhibits strong PPC with long-lasting recovery time, which leads the appearance of the conductor-like behaviour in ZTO semiconductor. In the present case, the conductivity changes over six orders of magnitude, from ~ 10⁻⁷ to 0.92/Ω/cm. After UV exposure, the ZTO compound can potentially remain in the conducting state for up to a month. The underlying physics of the observed PPC effect is investigated by studying defects (deep states and tail states) by employing a discharge current analysis (DCA) technique. Findings from the DCA study reveal direct evidence for the involvement of sub-bandgap tail states of the ZTO in the strong PPC, while deep states contribute to mild PPC.

我们报告了在氧化锌锡 (ZTO) 薄膜光电晶体管中出现的强持久光电导 (PPC) 和类似导体的行为。有源ZTO沟道层是通过远程等离子体反应溅射制备的，具有非晶结构。在用紫外光对 ZTO 进行亚带隙激发下，光电流高达 ~ 10 ^-4 A（光暗电流比为 ~ 10 ⁷）并且在关掉光后保持接近这个高值。在此期间，ZTO TFT 表现出强大的 PPC 和持久的恢复时间，这导致 ZTO 半导体中出现类似导体的行为。在目前的情况下，电导率变化超过六个数量级，从 ~ 10 ^-7到 0.92/Ω/cm。紫外线照射后，ZTO 化合物可能会保持导电状态长达一个月。通过使用放电电流分析 (DCA) 技术研究缺陷（深态和尾态）来研究观察到的 PPC 效应的基础物理。DCA 研究的结果揭示了 ZTO 的子带隙尾态参与强 PPC 的直接证据，而深态有助于轻度 PPC。