One-Step Synthesis Of Nbse2/Nb-Doped-Wse2 Metal/Doped-Semiconductor Van Der Waals Heterostructures For Doping Controlled Ohmic Contact

van der Waals heterostructures (vdWHs) of metallic (m-) and semiconducting (s-) transition-metal dichalcogenides (TMDs) exhibit an ideal metal/semiconductor (M/S) contact in a field-effect transistor. However, in the current two-step chemical vapor deposition process, the synthesis of m-TMD on pregrown s-TMD contaminates the van der Waals (vdW) interface and hinders the doping of s-TMD. Here, NbSe2/Nb-doped-WSe2 metal-doped-semiconductor (M/d-S) vdWHs are created via a one-step synthesis approach using a niobium molar ratio-controlled solution-phase precursor. The one-step growth approach synthesizes Nb-doped WSe2 with a controllable doping concentration and metal/doped-semiconductor vdWHs. The hole carrier concentration can be precisely controlled by controlling the Nb/(W + Nb) molar ratio in the precursor solution from similar to 3 x 10(11)/cm(2) at Nb-0% to similar to 1.38 x 10(12)/cm(2) at Nb-60%; correspondingly, the contact resistance R-C value decreases from 10 888.78 at Nb-0% to 70.60 k Omega.mu m at Nb-60%. The Schottky barrier height measurement in the Arrhenius plots of ln(I-sat/T-2) versus q/KBT demonstrated an ohmic contact in the NbSe2/WxNb1-xSe2 vdWHs. Combining p-doping in WSe2 and M/d-S vdWHs, the mobility (27.24 cm(2) V-1 s(-1)) and on/off ratio (2.2 x 10(7)) are increased 1238 and 4400 times, respectively, compared to that using the Cr/pure-WSe2 contact (0.022 cm(2) V-1 s(-1) and 5 x 10(3), respectively). Together, the R-C value using the NbSe2 contact shows 2.46 k Omega.mu m, which is similar to 29 times lower than that of using a metal contact. This method is expected to guide the synthesis of various M/d-S vdWHs and applications in future high-performance integrated circuits.