Substrate Effects on the Speed Limiting Factor of WSe${}_2$ Photodetectors

Abstract

We investigate the time-resolved photoelectric response of WSe${}_2$ crystals on common glass and flexible polyimide substrates to determine the effect of the dielectric environment on the speed of the photodetectors. We show that varying the substrate material can alter the speed-limiting mechanism: while the detectors on polyimide are RC limited, those on glass are limited by slower excitonic diffusion processes. We attribute this to a shortening of the depletion layer at the metal electrode/WSe2 interface caused by the higher dielectric screening of glass compared to polyimide. The photodetectors on glass show a tunable bandwidth which can be increased to 2.6 MHz with increasing the electric field.

arXiv comment27 pages, 13 figures

References in corpus (12)

• Boron nitride substrates for high-quality graphene electronics
• Exciton Binding Energy and Nonhydrogenic Rydberg Series in Monolayer WS2
• Optical Spectrum of MoS${}_2$: Many-body Effects and Diversity of Exciton States
• Measurement of the optical dielectric function of transition metal dichalcogenide monolayers: MoS2, MoSe2, WS2 and WSe2
• Elastic properties of freely suspended MoS2 nanosheets
• The Nature of Electronic States in Atomically Thin MoS2 Field-Effect Transistors
• High Mobility Ambipolar MoS2 Field-Effect Transistors: Substrate and Dielectric Effects
• Anomalous Raman Spectra and Thickness Dependent Electronic properties of WSe2
• Enhancement of Carrier Mobility in Semiconductor Nanostructures by Dielectric Engineering
• Measurement of high exciton binding energy in the monolayer transition-metal dichalcogenides WS2 and WSe2
• A strain tunable single-layer MoS2 photodetector
• Environmental effects on the electrical characteristics of back-gated WSe2 field effect transistors