Two-dimensional (2D) materials represent an exceptional class of nano materials, defined by being one to two atoms thick, that will have a critical role in electronic, optoelectronic, and photonic applications and technologies. The ability to tune the electronic properties of these 2D materials via contact doping in Van der Waals heterostructures and chemical doping in monolayers provides a great future for next generation (post-silicon) electronics. Because of their thickness and rigidness, current silicon devices are very cost inefficient and inappropriate for developing novel, thin, and flexible devices. Using synchrotron-based X-ray techniques to examine Van der Waals heterostructures and doped monolayers, we have further defined the dopant bond type and atomistic concentrations of these structures. Findings have confirmed that the atomistic concentrations of our substitutional chemically doped monolayers were 17% chemical dopant which coincides with Density Functional Theory calculations. We found that chemically doped monolayer samples and contact doped (Van der Waals heterostructures) samples were p-type and n-type, respectively. This finding suggests that, in direct application of these samples in potential devices, the n-type Van der Waals heterostructures would greatly increase conductivity, thus generating a better charge transport, which is optimal for electronic devices. These results demonstrate that both chemical and contact doping affect the optoelectronic properties of Van der Waals heterostructures and 2D monolayers. Further studies will characterize contact doping in heterostructures, because contact doping shifts the original bond types to n-type doping. These potential findings are critical for improving the applications of these 2D materials in electronic devices.

Comparing the effects of chemical doping and contact doping in 2D monolayers

2019 Spring National Meeting

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