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Published October 12, 2016 | Submitted
Journal Article Open

Enhanced Thermionic-Dominated Photoresponse in Graphene Schottky Junctions

Abstract

Vertical heterostructures of van der Waals materials enable new pathways to tune charge and energy transport characteristics in nanoscale systems. We propose that graphene Schottky junctions can host a special kind of photoresponse that is characterized by strongly coupled heat and charge flows that run vertically out of the graphene plane. This regime can be accessed when vertical energy transport mediated by thermionic emission of hot carriers overwhelms electron–lattice cooling as well as lateral diffusive energy transport. As such, the power pumped into the system is efficiently extracted across the entire graphene active area via thermionic emission of hot carriers into a semiconductor material. Experimental signatures of this regime include a large and tunable internal responsivity R with a nonmonotonic temperature dependence. In particular, R peaks at electronic temperatures on the order of the Schottky barrier potential ϕ and has a large upper limit R ≤ e/ϕ (e/ϕ = 10 A/W when ϕ = 100 meV). Our proposal opens up new approaches for engineering the photoresponse in optically active graphene heterostructures.

Additional Information

© 2016 American Chemical Society. Received: May 13, 2016; Revised: September 3, 2016; Published: September 6, 2016. We are grateful for useful discussions with M. Baldo, M. Kats, and L. Levitov. We also thank V. Fatemi, A. Frenzel, and K. Tielrooij for a critical reading of the text. J.F.R.N. and M.S.D. acknowledge financial support from the National Science Foundation Grant DMR-1507806. J.C.W.S. acknowledges support from a Burke Fellowship at Caltech. The authors declare no competing financial interest.

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