Reflection of millimeter-range electromagnetic radiation from slightly doped gallium arsenide

The reflection coefficient R and the phase angleϕ of the reflected electromagnetic wave are calculated with an account of various scattering mechanisms (scattering by ionized impurity and by optical phonons) for wavelengths in the 2-mm range at room temperature. Simplified semiclassical equations for the complex reflection coefficient R* are shown to be valid. The equations are used to calculate R and ϕ for n-type GaAs as functions of the dimensionless frequencies y = ω/ωp and ωpτ. The experimental values of R and ϕ for n-type GaAs single crystals at 2.2 mm agree with the theoretical values, within the experimental error. The concentrations and mobilities determined from the experimental data agree well with the results of Hall measurements.