College of Materials Science and Engineering and Key Laboratory of Advanced Functional Materials, Education Ministry of China, Beijing University of Technology, Beijing, 100124, China.
Nanoscale. 2019 Nov 28;11(46):22531-22538. doi: 10.1039/c9nr07597f.
Floating-base bipolar transistors are widely used semiconductor devices because they could both amplify signal current and suppress noise. Employing two-dimensional (2D) materials of ultrahigh photoelectric properties could further improve the device performance. Due to the difficulty in doping, homojunctions are usually not realizable for many 2D materials. Instead, a heterojunction of various 2D materials of different Fermi levels is usually needed. However, the material interface of a heterojunction deteriorates device performance and makes the fabrication process difficult. Here, the doping difficulties have been solved by utilizing a solid ionic dielectric material (LiTaO3) and a floating-base bipolar transistor based on a 2D material (monolayer MoS2 here) homojunction is realized. The transistor shows tunable ambipolar transport characteristics. Particularly, under illumination, the amplification coefficient of a phototransistor can be optimized by changing the gate voltage. The optimized photoresponsivity of the device could reach up to 7.9 A W-1 with an ultrahigh detectivity of 3.39 × 1011 Jones. The overall fabrication processing is compatible to conventional processing. This design can effectively extend the application of 2D materials.
浮置基双极晶体管因其既能放大信号电流又能抑制噪声而被广泛应用于半导体器件。采用具有超高光电性能的二维（2D）材料可以进一步提高器件性能。由于掺杂困难，许多 2D 材料通常不能实现同质结。相反，通常需要不同费米能级的各种 2D 材料的异质结。然而，异质结的材料界面会恶化器件性能并使制造过程变得困难。在这里，通过利用固态离子介电材料（LiTaO3）和基于 2D 材料（这里是单层 MoS2）的浮置基双极晶体管同质结解决了掺杂困难。该晶体管表现出可调双极输运特性。特别是在光照下，通过改变栅极电压可以优化光电晶体管的放大系数。该器件的优化光响应度高达 7.9 A W-1，超高探测率达到 3.39×1011 Jones。整体制造工艺与传统工艺兼容。该设计可以有效地扩展 2D 材料的应用。
