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Fast response photogating in monolayer MoS2 phototransistors
Nanoscale ( IF 6.7 ) Pub Date : 2021-09-07 , DOI: 10.1039/d1nr03896f
Daniel Vaquero 1 , Vito Clericò 1 , Juan Salvador-Sánchez 1 , Elena Díaz 2 , Francisco Domínguez-Adame 2 , Leonor Chico 2, 3 , Yahya M Meziani 1 , Enrique Diez 1 , Jorge Quereda 1
Affiliation  

Two-dimensional transition metal dichalcogenide (TMD) phototransistors have been the object of intensive research during the last years due to their potential for photodetection. Photoresponse in these devices is typically caused by a combination of two physical mechanisms: the photoconductive effect (PCE) and photogating effect (PGE). In earlier literature for monolayer (1L) MoS2 phototransistors, PGE is generally attributed to charge trapping by polar molecules adsorbed to the semiconductor channel, giving rise to a very slow photoresponse. Thus, the photoresponse of 1L-MoS2 phototransistors at high-frequency light modulation is assigned to PCE alone. Here we investigate the photoresponse of a fully h-BN encapsulated monolayer (1L) MoS2 phototransistor. In contrast with previous understanding, we identify a rapidly-responding PGE mechanism that becomes the dominant contribution to photoresponse under high-frequency light modulation. Using a Hornbeck–Haynes model for the photocarrier dynamics, we fit the illumination power dependence of this PGE and estimate the energy level of the involved traps. The resulting energies are compatible with shallow traps in MoS2 caused by the presence of sulfur vacancies.

中文翻译:

单层二硫化钼光电晶体管中的快速响应光电门控

二维过渡金属二硫属化物 (TMD) 光电晶体管由于其在光电检测方面的潜力,在过去几年中一直是深入研究的对象。这些器件中的光响应通常由两种物理机制的组合引起:光电导效应 (PCE) 和光门控效应 (PGE)。在关于单层 (1L) MoS 2光电晶体管的早期文献中,PGE 通常归因于吸附到半导体通道的极性分子捕获电荷,从而导致非常缓慢的光响应。因此,1L-MoS 2光电晶体管在高频光调制下的光响应仅分配给PCE。在这里,我们研究了完全 h-BN 封装的单层 (1L) MoS 2的光响应光电晶体管。与之前的理解相反,我们确定了一种快速响应的 PGE 机制,该机制在高频光调制下成为对光响应的主要贡献。使用用于光载流子动力学的 Hornbeck-Haynes 模型,我们拟合该 PGE 的照明功率依赖性并估计所涉及陷阱的能级。由此产生的能量与由硫空位的存在引起的MoS 2 中的浅陷阱相容。
更新日期:2021-09-21
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