Issue 10, 2023

Homogeneous in-plane WSe2 P–N junctions for advanced optoelectronic devices

Abstract

Conventional doping schemes of silicon (Si) microelectronics are incompatible with atomically thick two-dimensional (2D) transition metal dichalcogenides (TMDCs), which makes it challenging to construct high-quality 2D homogeneous p–n junctions. Herein, we adopt a simple yet effective plasma-treated doping method to seamlessly construct a lateral 2D WSe2 p–n homojunction. WSe2 with ambipolar transport properties was exposed to O2 plasma to form WOx on the surface in a self-limiting process that induces hole doping in the underlying WSe2via electron transfer. Different electrical behaviors were observed between the as-exfoliated (ambipolar) region and the O2 plasma-treated (p-doped) region under electrostatic modulation of the back-gate bias (VBG), which produces a p–n in-plane homojunction. More importantly, a small contact resistance of 710 Ω μm with a p-doped region transistor mobility of ∼157 cm2 V−1 s−1 was achieved due to the transformation of Schottky contact into Ohmic contact after plasma treatment. This effectively avoids Fermi-level pinning and significantly improves the performance of photodetectors. The resultant WSe2 p–n junction device thus exhibits a high photoresponsivity of ∼7.1 × 104 mA W−1 and a superior external quantum efficiency of ∼228%. Also, the physical mechanism of charge transfer in the WSe2 p–n homojunction was analyzed. Our proposed strategy offers a powerful route to realize low contact resistance and high photoresponsivity in 2D TMDC-based optoelectronic devices, paving the way for next-generation atomic-thickness optoelectronics.

Graphical abstract: Homogeneous in-plane WSe2 P–N junctions for advanced optoelectronic devices

Supplementary files

Article information

Article type
Paper
Submitted
09 Nov 2022
Accepted
25 Jan 2023
First published
25 Jan 2023
This article is Open Access
Creative Commons BY-NC license

Nanoscale, 2023,15, 4940-4950

Homogeneous in-plane WSe2 P–N junctions for advanced optoelectronic devices

D. Yue, X. Ju, T. Hu, X. Rong, X. Liu, X. Liu, H. K. Ng, D. Chi, X. Wang and J. Wu, Nanoscale, 2023, 15, 4940 DOI: 10.1039/D2NR06263A

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