混合维度WS_(2)/WSe_(2)/Si单极势垒异质结构用于高性能光电探测

Mixed-dimensional WS_(2)/WSe_(2)/Si unipolar barrier heterostructure for high-performance photodetection

单极势垒异质结构可以选择性地降低暗电流,但不影响光电流,是一种构建高性能光电探测器的有效策略.特别地,具有可调谐能带结构和自钝化表面的二维(2D)材料不仅能满足能带匹配要求,而且避免了界面缺陷和晶格失配,有助于设计单极势垒异质结构.这里,我们展示了一种混合维度WS_(2)/WSe_(2)/p-Si单极势垒异质结光电探测器.其中,2D WS_(2)充当光子吸收体,原子级厚度的WSe_(2)充当单极势垒,3D p-Si充当光生载流子收集器.插入的WSe_(2)不仅减轻了有害的衬底效应,而且形成了高导带势垒,可以过滤掉若干暗电流分量,同时不影响光电流.在隧穿效应和载流子倍增效应的驱动下,该WS_(2)/WSe_(2)/p-Si器件表现出高于10~5的高开/关比、2.39×10^(12)Jones的高探测度和8.47/7.98毫秒的快速上升/衰减时间.这些优点显著优于传统的WS_(2)/p-Si器件,为设计高性能的光电器件开辟了一个新方案.

The use of unipolar barrier structures that can selectively block dark current but allow photocurrent to flow unimpededly has emerged as an effective strategy for constructing high-performance photodetectors.In particular,two-dimensional(2D)materials with tunable band structures and self-passivated surfaces not only satisfy band-matching requirements but also avoid interface defects and lattice mismatches,which are attractive for designing unipolar barriers.Here,we demonstrate a mixed-dimensional WS_(2)/WSe_(2)/p-Si unipolar barrier photodetector,in which 2D WS_(2)acts as the photon absorber,atomically thin WSe_(2)as the unipolar barrier,and 3D p-Si as the photogenerated carrier collector.The intercalated WSe_(2)not only mitigates detrimental substrate effects but also forms a high-conduction band barrier to filter out several dark current components with the photocurrent flowing unimpededly.Driven by tunneling and carrier multiplication effects,the WS_(2)/WSe_(2)/p-Si device exhibits a high light on/off ratio above 10~5,a high detectivity of 2.39×10^(12)Jones,and a fast rise/decay time of 8.47/7.98 ms.These figures of merit are significantly improved over the conventional WS_(2)/p-Si device,opening up an effective scheme for designing high-performance optoelectronic devices.