Graduate Student Robert Hamburger

"2-D Materials: Modifying Charge Carriers in Transition Metal Dichalcogenides Through Molecular Interaction"

Since the inception of computers early in the 20th century electronic components have rapidly decreased in size allowing computers to become smaller even while increasing in power. In 1965, Gordon E. Moore predicted that the number of transistors on a computer component would double every 2 years. Even though he intended for his prediction to only hold for 10 years, it has held up to the present. Transistor size has decreased to the point of reaching the minimal size achievable by traditional materials (such as Silicon). Two-dimensional (2-D) materials present a promising avenue for continued miniaturization in transistors. Within this field, transition metal dichalcogenides (TMDs) represent a promising target due to the wide range of possible material combinations that can be synthesized to produce new materials with useful electronic and optoelectronic properties. One key to deployment of actual devices is the control and tuning of these properties through doping and the modification of charge carrier type. I will present three strategies for altering charge carrier type using a molecular chemistry approach.1 Physisorption of small molecules onto the surface of TMDs can allow for dynamic doping of the material without introducing additional defects. Further characterization of this process allows for the understanding of how washes and protective coatings may contribute to additional doping.2-3 Molecular scaffolds can be used to achieve doping through dipole interactions of adsorbed molecules.4-5 Finally covalent functionalization of 2-D TMDs at defect sites in the material can also achieve doping. Defect engineering can be used to control the density of defects allowing generation of more pristine materials needed for device application.6-7

1. Bertolazzi S, et al. Chemical Society Reviews. 47, 6845-6888 (2018)
2. Wang Y, et al. Journal of Physical Chemistry Letters. 10, 540-547 (2019)
3. Dien V, et al. Journal of Computational Electronics. 20, 135-150 (2021)
4. Wang Y, et al. Advanced Functional Materials. 30, 2002846 (2020)
5. Brill A, et al. ACS Applied Materials and Interfaces. 13, 32590-32597 (2021)
6. Chen X, et al. Chemistry A European Journal. 26, 6535-6544 (2020)
7. Park Y, et al. ACS Applied Materials and Interfaces. 12, 40870-40878 (2020)