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arXiv · 1611.01589

Photodetection in p-n junctions formed by electrolyte-gated transistors of two-dimensional crystals

Daichi Kozawa·Jiang Pu·Ryo Shimizu·Shota Kimura·Ming-Hui Chiu·Keiichiro Matsuki·Yoshifumi Wada·Tomo Sakanoue·Yoshihiro Iwasa·Lain-Jong Li·Taishi Takenobu
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Abstract

Transition metal dichalcogenide (TMDC) monolayers have attracted much attention due to their strong light absorption and excellent electronic properties. These advantages make this type of two-dimensional crystal a promising one for optoelectronic device applications. In the case of photoelectric conversion devices such as photodetectors and photovoltaic cells, p-n junctions are one of the most important devices. Here, we demonstrate photodetection with WSe2 monolayer films. We prepare the electrolyte-gated ambipolar transistors and electrostatic p-n junctions are formed by the electrolyte-gating technique at 270 K. These p-n junctions are cooled down to fix the ion motion (and p-n junctions) and we observed the reasonable photocurrent spectra without the external bias, indicating the formation of p-n junctions. Very interestingly, two-terminal devices exhibit higher photoresponsivity than that of three-terminal ones, suggesting the formation of highly balanced anion and cation layers. The maximum photoresponsivity reaches 5 mA/W in resonance with the first excitonic peak. Our technique provides important evidence for optoelectronics in atomically thin crystals.

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Daichi Kozawa, Jiang Pu, Ryo Shimizu, Shota Kimura, Ming-Hui Chiu, Keiichiro Matsuki, Yoshifumi Wada, Tomo Sakanoue, Yoshihiro Iwasa, Lain-Jong Li, Taishi Takenobu. 2016-11-05. Photodetection in p-n junctions formed by electrolyte-gated transistors of two-dimensional crystals. https://doi.org/10.1063/1.4967173

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