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Extracting Electron Densities in N-Type GaAs from Raman Spectra: Theory



Herbert S. Bennett


Raman measurements are proposed as a non-destructive method for wafer acceptance tests of carrier density. The interpretation of Raman spectra to determine the majority electron density in n-type semiconductors requires an interdisciplinary effort involving experiments, theory, and computer-based simulations and visualizations of the theoretical calculations. In this paper, we present the theory for calculating Raman line shapes as functions of the Fermi energy and temperature in zinc blende, n-type GaAs for donor densities between 10^16 cm^-3 and 10^19 cm^-3. These calculations solve the charge neutrality nist-equation self-consistently for a two-band model of GaAs at 300 K that includes the effects of high carrier concentrations and dopant densities on the perturbed densities of states used to calculate the Fermi energy as a function of temperature. The results are then applied to obtaining the carrier concentrations from Fermi energies in the context of line shapes in Raman spectra due to the coupling between longitudinal optic phonons and plasmons.
Journal of Research (NIST JRES) -


electron density, Fermi energy, gallium arsenide, phonon, Raman spectra, electric susceptibility, bandgap narrowing
Created July 1, 2007, Updated January 27, 2020