Doping induces large variation in the electrical properties of MoS2 monolayers

• It is difficult to precisely control the dopant position and number in 2D materials.
• Variation in dopant position causes large variation in electronic properties in MoS2.
• Variation in dopant number makes the variation even larger in MoS2 monolayers.
• The variation places a challenge on the application of doped 2D MoS2 in circuits.

As the devices are being shrunk into nanoscale, it is increasingly difficult, if not impossible, to precisely control the dopant position and number in low-dimensional nanomaterials. In this work, we have investigated doping effect on the electrical properties of n-type and p-type MoS2 monolayer, one of the representative two-dimensional layered semiconductors. We found that the sheet resistance of a nanoscale MoS2 monolayer exhibited large variation (>35%) as the dopant number or position changes, although the variation in band gap is relatively small. The variation increases as the size of MoS2 monolayer decreases. This variation in the doped MoS2 monolayer nanoribbons seems inevitable and will cause significant device-to-device variation that the integrated circuit cannot tolerate. This study also suggests that these two-dimensional semiconductors should be protected from unintentional or intentional doping if they are used in the transistors in future integrated circuits.

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