具有快响应速度和低暗电流的垂直MSM型CsPbBr_(3)薄膜光电探测器

Vertical MSM-type CsPbBr_(3)thin film photodetectors with fast response speed and low dark current

卤化物钙钛矿具有优异的电学和光学性能,是光电子器件中理想的有源层候选材料,特别是在高性能光探测方面显示出更具竞争力的发展前景,其中全无机钙钛矿CsPbBr_(3)因其良好的环境稳定性而被广泛关注.本文报道了一种具有快响应速度和低暗电流的垂直MSM型CsPbBr_(3)薄膜光电探测器.由于采用垂直结构缩短了光生载流子的渡越距离,器件具有超快的响应速度63μs,比传统平面MSM型光电探测器提高了两个数量级.然后,通过在p型CsPbBr_(3)与Ag电极之间旋涂一层TiO_(2)薄膜,提升了界面光生载流子的分离效率,实现了钙钛矿薄膜与金属电极间的物理钝化,从而大大降低了器件的暗电流,在–1 V的偏压下暗电流只有–4.81×10^(-12) A.此外,该种垂直MSM型CsPbBr_(3)薄膜光电探测器还具有线性动态范围大(122 dB)、探测率高(1.16×10^(12) Jones)和光稳定性好等诸多优点.通过Sentaurus TCAD模拟发现,电荷传输层可以选择性的阻挡载流子传输,从而起到降低暗电流的作用,Sentaurus TCAD模拟结果与实验数据吻合,揭示了电荷传输层降低器件暗电流的内在物理机制.

Halide perovskites exhibit excellent electrical and optical properties and are ideal candidates for active layers in optoelectronic devices,especially in the field of high-performance photodetection,where they demonstrate a competitive advantage in terms of development prospects.Among them,the all-inorganic perovskite CsPbBr_(3)has received widespread attention due to its better environmental stability.It is demonstrated in this work that a vertical MSM-type CsPbBr_(3)thin-film photodetector has characteristics of fast response time and ultra-low dark current.The use of a vertical structure can reduce the transit distance of photo carriers,enabling the device to achieve a fast response time of 63μs,which is two orders of magnitude higher than the traditional planar MSM-type photodetectors with a response time of 10 ms.Then,by spinning a charge transport layer between the p-type CsPbBr_(3)and Ag electrodes,effective separation of photocarriers at the interface is realized and physical passivation between the perovskite and metal electrodes is also achieved.Due to the superior surface quality of the spun TiO_(2) film compared with the NiO_(x) film,and through Sentaurus TCAD simulations and bandgap analyses,with TiO_(2) serving as the electron transport layer,it effectively inhibits the transmission of excess holes in p-type CsPbBr_(3).Consequently,the electron transport layer TiO_(2) is more effective in reducing dark current than the hole transport layer NiO_(x),with a dark current magnitude of only–4.81×10^(-12) A at a–1 V bias.Furthermore,this vertical MSM-type CsPbBr_(3)thin-film photodetector also has a large linear dynamic range(122 dB),high detectivity(1.16×10^(12) Jones),and good photo-stability.Through Sentaurus TCAD simulation,it is found that the charge transport layer selectively blocks carrier transmission,thereby reducing dark current.The simulation results are in good agreement with experimental data,providing theoretical guidance for a more in-depth understanding of the intrinsic physical mechanisms.