In recent years, MoS2 has emerged as a prime material for photodetector as well as phototransistor applications. Usually, the higher density of state and relatively narrow bandgap of multi-layer MoS2 give it an edge over monolayer MoS2 for phototransistor applications. However, MoS2 demonstrates thickness-dependent energy bandgap properties, with multi-layer MoS2 having indirect bandgap characteristics and therefore possess inferior optical properties. Herein, we investigate the electrical as well as optical properties of single-layer and multi-layer MoS2-based phototransistors and demonstrate improved optical properties of multi-layer MoS2 phototransistor through the use of see-through metal electrode instead of the traditional global bottom gate or patterned local bottom gate structures. The see-through metal electrode utilized in this study shows transmittance of more than 70% under 532 nm visible light, thereby allowing the incident light to reach the entire active area below the source and drain electrodes. The effect of contact electrodes on the MoS2 phototransistors was investigated further by comparing the proposed electrode with conventional opaque electrodes and transparent IZO electrodes. A position-dependent photocurrent measurement was also carried out by locally illuminating the MoS2 channel at different positions in order to gain better insight into the behavior of the photocurrent mechanism of the multi-layer MoS2 phototransistor with the transparent metal. It was observed that more electrons are injected from the source when the beam is placed on the source side due to the reduced barrier height, giving rise to a significant enhancement of the photocurrent.

中文翻译：

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具有透明金属电极的多层MoS2光电晶体管的改进的光学性能。

近年来，MoS2已经成为光电探测器以及光电晶体管应用的主要材料。通常，多层MoS2的较高的态密度和相对较窄的带隙使其在单晶体管MoS2上具有优势，适用于光电晶体管应用。然而，MoS 2表现出取决于厚度的能带隙特性，其中多层MoS 2具有间接带隙特性，因此具有较差的光学特性。在本文中，我们研究了基于单层和多层MoS2的光电晶体管的电学和光学特性，并通过使用透明金属电极代替了传统的全局底栅，展示了多层MoS2光电晶体管的改进的光学特性。或图案化的局部底栅结构。本研究中使用的透明金属电极在532 nm可见光下显示出超过70％的透射率，从而使入射光到达源电极和漏电极下方的整个有源区域。通过将建议的电极与常规的不透明电极和透明IZO电极进行比较，进一步研究了接触电极对MoS2光电晶体管的影响。还通过局部照射不同位置的MoS2通道来进行位置相关的光电流测量，以便更好地了解带有透明金属的多层MoS2光电晶体管的光电流机制。可以观察到，由于势垒高度减小，当电子束放在源侧时，从源注入了更多的电子，