Xie Binghe, Wu Jiaxin, Mei Junning, Zhu Shuangxing, Zhang Ruan, Gu Feifan, Watanabe Kenji, Taniguchi Takashi, Cai Xinghan
National Key Laboratory of Advanced Micro and Nano Manufacture Technology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China.
Department of Micro/Nano Electronics, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China.
Nano Lett. 2024 Mar 6;24(9):2870-2875. doi: 10.1021/acs.nanolett.3c05131. Epub 2024 Feb 26.
Leveraging its ultrahigh carrier mobility, zero-bandgap linear dispersion, and extremely short response time, graphene exhibits remarkable potential in ultrafast broad-band photodetection. Nonetheless, the inherently low responsivity of graphene photodetectors, due to the low photogenerated carrier density, significantly impedes the development of practical devices. In this study, we present an improved photoresponse within a graphene-hexagonal boron nitride-graphene vertical tunnel junction device, where the crystallographic orientation of the two graphene electrodes is aligned. Through meticulous device structure design and the adjustment of bias and gate voltages, we observe a 2 orders of magnitude increase in tunneling photocurrent, which is attributed to the momentum-conserving resonant electron tunneling. The enhanced external photoresponsivity is evident across a wide temperature and spectral range and achieves 0.7 A/W for visible light excitation. This characteristic, coupled with the device's negative differential conductance, suggests a novel avenue for highly efficient photodetection and high-frequency, logic-based optoelectronics using van der Waals heterostructures.
凭借其超高的载流子迁移率、零带隙线性色散和极短的响应时间，石墨烯在超快宽带光电探测方面展现出巨大潜力。然而，由于光生载流子密度低，石墨烯光电探测器固有的低响应度严重阻碍了实际器件的发展。在本研究中，我们展示了一种在石墨烯-六方氮化硼-石墨烯垂直隧道结器件中得到改善的光响应，其中两个石墨烯电极的晶体取向是对齐的。通过精心的器件结构设计以及偏置电压和栅极电压的调整，我们观察到隧穿光电流增加了两个数量级，这归因于动量守恒的共振电子隧穿。增强的外部光响应在很宽的温度和光谱范围内都很明显，对于可见光激发，其光响应度达到了0.7 A/W。这一特性，再加上器件的负微分电导，为使用范德华异质结构的高效光电探测以及基于高频逻辑的光电子学开辟了一条新途径。
