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) Variation of the current in linear scale (black curve) and the current in logarithmic scale (blue curve) with both bottom gate voltages (V_lg = V_rg = V_g) at voltage bias V_sd = 500 mV, showing an ambipolar behavior expected for a semiconductor. (b) I–V characteristics of the monolayer WSe₂ p–n junction device in the dark for different doping configurations: black curve: V_lg = V_rg = −6 V (PP), red curve: V_lg = −4 V, V_rg = 6 V (PN), blue curve: V_lg = 6 V, V_rg = −4 V (NP). (c) Main panel: I–V characteristics at different PN junction fields as controlled by the two bottom split-gate voltages (black curve: V_lg = −4 V, V_rg = 6 V; blue curve: V_lg = −3 V, V_rg = 5 V). Inset panel: I–V characteristics at different NP junction fields (magenta curve: V_lg = 6 V, V_rg = −4 V; green curve: V_lg = 5 V, V_rg = −3 V). (d) Schematic band diagram of the WSe₂ junction in the PN regime showing a distortion of the WSe₂’s band V_th(l) and V_th(r), denoting two threshold voltages of bottom gates which can tune the WSe₂ to p-type and n-type regimes respectively, are estimated from the current in logarithmic scale (blue curve) shown in Fig. 2(a).