Abstract
Infrared transmission measurements are made in the range from 400 to 4000 cm−1 in GaAs, GaP and their alloys. A tentative assignment of the infrared absorption spectrum is performed taking the physical properties of crystal symmetry into account. The integrated absorptions of the two-optical phonon combination bands obtained for GaAs and GaP are approximately an order of magnitude larger than that of silicon. The values of anharmonic parameter determined from a comparison between Kleinman’s theory and experimental data are 3.2 for GaP and 3.1±0.3 for GaAs in 1012 g cm−1 sec−2. Some of thermodynamic properties, that is, Grüneisen constant, compressibility and linear thermal expansion coefficient, are estimated on the basis of the anharmonic model. These theoretical values are reasonable in comparison with the experimental ones.
