Bipolar phototransistors have higher optical responsivity than photodiodes and play an important role in the field of photoelectric conversion. Two-dimensional materials offer a good optical responsivity and have the potential advantages of heterogeneous integration, but mass-production is difficult. In this study, a bipolar phototransistor is presented based on a vertical Au/graphene/MoS2 van der Waals heterojunction that can be mass-produced with a silicon semiconductor process using a simple photolithography process. Au is used as the emitter, which is a functional material used not just for the electrodes, MoS2 is used for the collector, and graphene in used for the base of the bipolar phototransistor. In the bipolar phototransistor, the electric field of the dipole formed by the Au and graphene contact is in the same direction as the external electric field and thus enhances the photocurrent, and a maximum photocurrent gain of 18 is demonstrated. A mechanism for enhancing the photocurrent of the graphene/MoS2 photodiode by contacting Au with graphene is also described. Additionally, the maximum responsivity is calculated to be 16,458 A/W, and the generation speed of the photocurrent is 1.48×10−4 A/s.

中文翻译：

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具有光电流增强功能的垂直 Au/石墨烯/MoS2 范德华异质结中的双极光电晶体管

双极光电晶体管具有比光电二极管更高的光学响应度，在光电转换领域发挥着重要作用。二维材料具有良好的光学响应性和异构集成的潜在优势，但量产难度较大。在这项研究中，提出了一种基于垂直 Au/石墨烯/MoS2 范德华异质结的双极光电晶体管，该异质结可以使用简单的光刻工艺通过硅半导体工艺进行批量生产。Au用作发射极，它是一种功能材料，不仅用于电极，MoS2用作集电极，石墨烯用作双极光电晶体管的基极。在双极光电晶体管中，Au和石墨烯接触形成的偶极子的电场与外部电场的方向相同，从而增强了光电流，最大光电流增益为18。还描述了通过将 Au 与石墨烯接触来增强石墨烯/MoS2 光电二极管的光电流的机制。此外，计算出的最大响应率为16,458 A/W，光电流的产生速度为1.48×10-4 A/s。