Recently, ferroelectric polarization coupling has been exploited for non-volatile p- and n-type doping of two-dimensional (2D) materials, which enables the design of 2D functional devices via a local polarization pattern. Here, we took advantage of this tool and study the effect of base width to the gain and photodetection performance of bipolar transistors made of few layer MoS₂. We found that the space charge region in the base have typical width ∼150–250 nm, and depends on the applied external bias. Such a characteristic causes the compromise between transistor gain and shunt resistance when changing the base width. For photodetection, this hinders the optimization of responsivity without increasing the dark current. As a result, an optimal device was made at the base width ∼1040 nm, from which a responsivity of 160 A W⁻¹, specific detectivity of ∼1.3 10¹² and the response time ∼9 μs to 680 nm incident light was obtained. The results from the present study shed light on the further design of 2D functional devices that use lateral pn junctions as the basic building blocks.

最近，铁电极极化耦合已被用于二维 (2D) 材料的非易失性 p 型和 n 型掺杂，这使得通过局部极化模式设计 2D 功能器件成为可能。在这里，我们利用该工具研究了基极宽度对由几层 MoS ₂制成的双极晶体管的增益和光电检测性能的影响. 我们发现基区中的空间电荷区的典型宽度约为 150-250 nm，并取决于施加的外部偏压。当改变基极宽度时，这种特性导致晶体管增益和分流电阻之间的折衷。对于光电检测，这会阻碍响应度的优化而不增加暗电流。结果，在基宽约1040 nm处制成了最佳器件，由此获得了160 AW ^-1的响应度、~ 1.3 10 ^{12 的} 比检测率和对680 nm入射光的响应时间~9 μ s。本研究的结果阐明了使用横向 pn 结作为基本构建块的 2D 功能器件的进一步设计。