How to Make Tungsten Disulfide Transistor?

Tungsten disulfide transistor is made by stripping monolayer tungsten disulfide from tungsten disulfide. And electron beam lithography is applied in the making process. WS₂ transistor with good optoelectronic performance can be used in the optoelectronic devices.

Lithography is an important technology applied in the production of planar transistor and integrated circuit. It involves the opening of semiconductor chip surface, which helps the local diffusion of impurities. Cleaning and drying of silicon wafer surface, soft-drying and hard-drying are the main working procedures.

Tungsten disulfide transistor can be prepared by the following steps:

Step One: The stripping of monolayer tungsten disulfide.

The material tungsten disulfide on adhesive tape is folded and polydimethylsiloxane (PDMS) is attached to the adhesive tape. Then, the tape is quickly uncovered to strip off monolayer tungsten disulfide from the material tungsten disulfide. Monolayer tungsten disulfide is prepared successfully in this way. And it is used to make the WS₂ transistor.

Step Two: The making of WS₂ transistor with electron beam lithography.The obtained monolayer tungsten disulfide is transferred to a p-type Si substrate covered with 300 nm SiO₂ by a sample transfer table.Laser excitation at 532 nm is used to detect whether it is monolayer or not. Electron beam lithography is applied to make tungsten disulfide transistor. Ti/Au (5/60 nm) electrodes are plated monolayer tungsten disulfide. The transistor has a channel length of 1.6 microns, together with a channel width of 6.8 microns.

In the making process of tungsten disulfide transistor. Monolayer tungsten disulfide has a direct band gap of about 2.0 eV, which can effectively suppress the leakage-to-source tunneling. The obtained n-type tungsten disulfide transistor has carrier mobility of 0.012 cm² V^-1S^-1, together with a switching ratio of 7.89 x 104. It is a transistor with good electrical transport performance, and has broad application value in the optoelectronic devices.

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