EFFECTIVE MASS ANISOTROPY AT THE X1C AND X3C MINIMA OF THE GALLIUM PHOSPHIDE CONDUCTION BAND.

Analytical expressions are derived for the spectra of optical absorption due to direct transitions of free carriers between bands with anistropic effective masses. A theoretical estimate is obtained of the ratio of the longitudinal effective masses at the X//1//C and X//3//C minima of the GaP conduction band: m//3//l/m//1//l approximately equals 0. 5. The theoretical results are used to analyze earlier information on the optical absorption due to X//1//C-X//3//C transitions of free electrons in GaP. It is shown that in this case the absorption line shape is determined by the transverse effective mass ratio: m//3//t/m//1//t approximately equals 0. 15.