Doping is a fundamental property of semiconductors and constitutes the basis of modern microelectronic and optoelectronic devices. Their miniaturization requires contactless characterization of doping with nanometer scale resolution. Here, we use low- and room-temperature cathodoluminescence (CL) measurements to analyze p-type and n-type GaAs thin films over a wide range of carrier densities (2×1017 to 1×1019 cm−3). The spectral shift and broadening of CL spectra induced by shallow dopant states and band filling are the signature doping. We fit the whole spectral lineshapes with the generalized Planck's law and refined absorption models to extract the bandgap narrowing (BGN) and the band tail for both doping types, and the electron Fermi level for n doping. This work provides a rigorous method for the quantitative assessment of p-type and n-type carrier density using CL. Taking advantage of the high spatial resolution of CL, it can be used to map the doping in GaAs nanostructures, and it could be extended to other semiconductor materials.
@article{arxiv.1909.05598,
title = {Quantitative Assessment of Carrier Density by Cathodoluminescence. I. GaAs thin films and modeling},
author = {Hung-Ling Chen and Andrea Scaccabarozzi and Romaric De Lépinau and Fabrice Oehler and Aristide Lemaître and Jean-Christophe Harmand and Andrea Cattoni and Stéphane Collin},
journal= {arXiv preprint arXiv:1909.05598},
year = {2022}
}