PhD Seminar - 2D Hole Gas on Hydrogen-Terminated Diamond: Electronic Structure and ARPES Insights

Hydrogen plasma treatment of diamond surfaces induces negative electron affinity due to a surface potential step. Naturally adsorbed H₂O acts as an electron acceptor, leading to downward band bending near the surface and the formation of a two-dimensional hole gas (2DHG). I will present our transport measurements, which display weak localization consistent with a 2DHG confined within a few nanometers of the surface. To directly probe this hole gas, we performed angle-resolved photoemission spectroscopy (ARPES). I will discuss the specific experimental challenges we had to overcome in order to measure these samples. While the observed electronic structure closely resembles that of bulk, three-dimensional diamond, I will show how confinement is still manifested in the experiment. I developed a model based on results from self-consistent Schrödinger–Poisson calculations and computed the ARPES intensity, demonstrating how confinement can produce a seemingly three-dimensional spectral signature.