LO phonon frequency of ZnSe thin films on GaAs grown by molecular beam epitaxy (MBE) has been measured from 20 to 300 K by Raman scattering. Frequency shift of the ZnSe LO phonon is estimated in terms of elastic strains due to lattice mismatch and thermal strains due to the difference in thermal expansion coefficients of film and substate. Strains due to lattice mismatch for thin films are dominant at high temperatures, while thermal strains due to large differences between growth and measurement temperatures are dominant at low temperatures. Temperature dependence of full witdh at half maximum (FWHM) in LO phonon spectra of ZnSe are discussed in terms of imperfection and phonon contribution.

The specific heat of InSe obeys the Debye model in the temperature region between 2 and 4.5 K. But it is explained as a superposition of the Debye and the Einstein models above 4.5 K. The Debye and the Einstein temperatures are 185 and 58 K, respectively. This Einstein temperature equals 40cm^-1 and corresponds to the energy ofE² mode observed in the Raman scattering experiments.