Abstract
Self-driven photodetectors that can detect light without any external voltage bias are important for low-power applications, including future internet of things, wearable electronics, and flexible electronics. While two-dimensional (2D) materials exhibit good optoelectronic properties, the extraordinary properties have not been fully exploited to realize high-performance self-driven photodetectors. In this paper, a metal–semiconductor–metal (MSM) photodetector with graphene and Au as the two contacts have been proposed to realize the self-driven photodetector. Van der Waals contacts are formed by dry-transfer methods, which is important in constructing the asymmetrical MSM photodetector to avoid the Fermi-level pinning effect. By choosing graphene and Au as the two contact electrodes, a pronounced photovoltaic effect is obtained. Without any external bias, the self-driven photodetector exhibits a high responsivity of 7.55 A W−1 and an ultrahigh photocurrent-to-dark current ratio of ~108. The photodetector also shows gate-tunable characteristics due to the field-induced Fermi-level shift in the constituent 2D materials. What is more, the high linearity of the photodetector over almost 60 dB suggests the easy integration with processing circuits for practical applications.
Highlights
Photodetectors that convert the light information into electrical information have been widely utilized in photography[1], optical communication[2], and analytical instruments[3]
Demonstrations used a back-gated field-effect transistor (FET) structure and the operational principle was mainly based on the photoconductive effect
The MSM structures are adopted for photodetectors due to the low dark current and a simple planar fabrication process[7]
Summary
Photodetectors that convert the light information into electrical information have been widely utilized in photography[1], optical communication[2], and analytical instruments[3]. To utilize the full light spectrum targeting emerging application fields such as biological imaging[9], environment monitoring[10], and flexible photodetectors[11], emerging semiconductor materials and device structures are being assessed on their suitability for photodetector development[12,13]. The main advantages of the PV effect-based photodetectors, including low dark current and small operating voltage, would enable a low-power or even self-driven photodetectors for applications in internet of things (IoT) and wearable electronics. 2D material-based self-driven photodetectors have received intense research efforts recently[23], and these photodetectors have exhibited superior performances in terms of responsivity, response time, and detectivity. The self-driven photodetector exhibits a gate-tunable PV effect thanks to the gate-tunable Fermi level of the 2D WSe2 and graphene. The fabrication of the proposed device structure does not involve any external chemical doping or complex split gate structure, ensuring a stable and low-cost process for self-driven photodetectors
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