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arXiv · 1805.09503

Charge Separation at Mixed-Dimensional Single and Multilayer MoS2/Silicon Nanowire Heterojunctions

Alex Henning·Vinod K. Sangwan·Hadallia Bergeron·Itamar Balla·Zhiyuan Sun·Mark C. Hersam·Lincoln J. Lauhon
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Abstract

Layered two-dimensional (2-D) semiconductors can be combined with other low-dimensional semiconductors to form non-planar mixed-dimensional van der Waals (vdW) heterojunctions whose charge transport behavior is influenced by the heterojunction geometry, providing a new degree of freedom to engineer device functions. Towards that end, we investigated the photoresponse of Si nanowire/MoS2 heterojunction diodes with scanning photocurrent microscopy and time-resolved photocurrent measurements. Comparison of n-Si/MoS2 isotype heterojunctions with p-Si/MoS2 heterojunction diodes under varying biases shows that the depletion region in the p-n heterojunction promotes exciton dissociation and carrier collection. We measure an instrument limited response time of 1 us, which is 10 times faster than previously reported response times for planar Si/MoS2 devices, highlighting the advantages of the 1-D/2-D heterojunction. Finite element simulations of device models provide a detailed understanding of how the electrostatics affect charge transport in nanowire/vdW heterojunctions and inform the design of future vdW heterojunction photodetectors and transistors.

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Alex Henning, Vinod K. Sangwan, Hadallia Bergeron, Itamar Balla, Zhiyuan Sun, Mark C. Hersam, Lincoln J. Lauhon. 2018-05-24. Charge Separation at Mixed-Dimensional Single and Multilayer MoS2/Silicon Nanowire Heterojunctions. https://doi.org/10.1021/acsami.8b03133

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