Modulation Doping of Single-Layer Semiconductors for Improved Contact at Metal Interfaces

Single layers of two-dimensional (2D) materials hold the promise for further miniaturization of semiconductor electronic devices. However, the metal-semiconductor contact resistance limits device performance. To mitigate this problem, we propose modulation doping, specifically a doping layer placed on the opposite side of a metal-semiconductor interface. Using firstprinciples calculations to obtain the band alignment, we show that the Schottky barrier height and, consequently, the contact resistance at the metal-semiconductor interface can be reduced by modulation doping. We demonstrate the feasibility of this approach for a single-layer tungsten diselenide (WSe2) channel and 2D MXene modulation doping layers, interfaced with several different metal contacts. Our results indicate that the Fermi level of the metal can be shifted across the entire band gap. This approach can be straight-forwardly generalized for other 2D semiconductors and a wide variety of doping layers.

Automated summary

The researchers propose a solution to the metal-semiconductor contact resistance problem, called modulation doping, by placing a doping layer on the opposite side of the metal-semiconductor interface. By using first-principles calculations, they demonstrate that modulation doping can reduce the Schottky barrier height and contact resistance at the metal-semiconductor interface. The feasibility of this approach is demonstrated for single-layer tungsten diselenide and 2D MXene materials, and it can be generalized for other 2D semiconductors.