Microscopic thickness determination of thin graphite films formed on SiC from quantized oscillation in reflectivity of low-energy electrons

TL;DR

This paper demonstrates a method using low-energy electron microscopy to precisely measure the thickness of thin graphite films on SiC by analyzing quantized oscillations in electron reflectivity.

Contribution

It introduces a microscopic technique to determine graphite film thickness based on reflectivity oscillations correlated with quantized conduction band states.

Findings

Quantized oscillations in reflectivity correlate with graphite thickness.

Resonance with quantized conduction band states causes dips in reflectivity.

The method aligns well with tight-binding and first-principles calculations.

Abstract

Low-energy electron microscopy (LEEM) was used to measure the reflectivity of low-energy electrons from graphitized 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 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.