Microscopic thickness determination of thin graphite films formed on<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>SiC</mml:mi></mml:mrow></mml:math>from quantized oscillation in reflectivity of low-energy electrons

TLDR

Conduction bands in thin graphite films form discrete energy levels whose wave vectors are normal to the surface. LEEM was used to measure low‑energy electron reflectivity from graphitized SiC(0001), and resonance with quantized conduction band states enhances transmission into the substrate, producing dips in reflectivity. Distinct quantized oscillations in reflectivity as a function of electron energy and graphite thickness were observed, with dip positions explained by tight‑binding and first‑principles calculations, allowing microscopic determination of graphite thickness distribution.

Abstract

Low-energy electron microscopy (LEEM) was used to measure the reflectivity of low-energy electrons from graphitized $\mathrm{SiC}(0001)$. The reflectivity shows distinct quantized oscillations as a function of the electron energy and graphite thickness. Conduction bands in thin graphite films form discrete energy levels whose wave vectors are normal to the surface. Resonance of the incident electrons with these quantized conduction band states enhances electrons to transmit through the film into the $\mathrm{SiC}$ substrate, resulting in dips in the reflectivity. The dip positions are well explained using tight-binding and first-principles calculations. The graphite thickness distribution can be determined microscopically from LEEM reflectivity measurements.