In optoelectronic devices based on two-dimensional (2D) semiconductor heterojunctions, the efficient charge transport of photogenerated carriers across the interface is a critical factor to determine the device performances. Here, we report an unexplored approach to boost the optoelectronic device performances of the WSe2-MoS2 p-n heterojunctions via the monolithic-oxidation-induced doping and resultant modulation of the interface band alignment. In the proposed device, the atomically thin WOx layer, which is directly formed by layer-by-layer oxidation of WSe2, is used as a charge transport layer for promoting hole extraction. The use of the ultrathin oxide layer significantly enhanced the photoresponsivity of the WSe2-MoS2 p-n junction devices, and the power conversion efficiency increased from 0.7 to 5.0%, maintaining the response time. The enhanced characteristics can be understood by the formation of the low Schottky barrier and favorable interface band alignment, as confirmed by band alignment analyses and first-principle calculations. Our work suggests a new route to achieve interface contact engineering in the heterostructures toward realizing high-performance 2D optoelectronics.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation (NRF) of Korea (2017R1A5A1014862 (SRC Program: vdWMRC Center), 2017R1D1A1B03035441, and 2018M3D1A1058793), the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20173010013340), the Korea University Grant and the KU-KIST School Project. S.H. acknowledges support from the NRF of Korea (2018K1A4A3A01064272 (GRDC Program), 2017R1A2B2010123, 2010-0020207 (Priority Research Center Program)). H.Y.J. acknowledges support from the NRF of Korea (2018R1A2B6008104). H.-G.P. acknowledges support from the NRF grant funded by the Korean government (MSIT) (2018R1A3A3000666). G.-H.L. acknowledges support from the Creative-Pioneering Researchers Program through Seoul National University (SNU).
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanical Engineering