Optoelectronic properties of bottom gate-defined in-plane monolayer WSe<sub>2</sub> p–n junction<xref rid="cpb_27_8_087303fn1" ref-type="fn">*</xref><fn id="cpb_27_8_087303fn1"><label>*</label><p>Project supported by the National Key Research and Development Program of China (Grant No. 2016YFA0301700), the National Natural Science Foundation of China (Grant Nos. 61590932, 11774333, 61674132, 11674300, 11575172, and 11625419), the Anhui Provincial Initiative in Quantum Information Technologies, China (Grant Nos. AHY080000 and AHY130300), the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB24030601), and the Fundamental Research Funds for the Central Universities, China. This work was partially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication.</p></fn>

Optoelectronic properties of bottom gate-defined in-plane monolayer WSe₂ p–n junction**

Project supported by the National Key Research and Development Program of China (Grant No. 2016YFA0301700), the National Natural Science Foundation of China (Grant Nos. 61590932, 11774333, 61674132, 11674300, 11575172, and 11625419), the Anhui Provincial Initiative in Quantum Information Technologies, China (Grant Nos. AHY080000 and AHY130300), the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB24030601), and the Fundamental Research Funds for the Central Universities, China. This work was partially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication.

Liu Di^{1, 2}, Qi Xiao-Zhuo^{1, 2}, Taniguchi Takashi³, Ren Xi-Feng^{1, 2, †}, Guo Guo-Ping^{1, 2, ‡}

(color online) (a) Van der Waals pick-up transfer process. (b) (i) Lateral view and (ii) optical microscope image of the monolayer WSe₂ p–n junction device. (d = 500 nm, black dashed line: outline of monolayer WSe₂, yellow dashed line: outline of bottom-layer h-BN, cyan dashed line: outline of top-layer h-BN, purple dashed line: outline of graphite, gold area: separated bottom gates.) (iii) SEM image after etching top-layer h-BN (green dashed line: outline of graphite after etching top-layer h-BN). (iv) SEM image after evaporation in-situ. (c) Raman shift and PL spectrum, showing the characteristic of monolayer WSe₂, with inset indicating the magnified gray dotted line area. The unit a.u. is short for arb. units.