Infrared ellipsometry and Raman studies of hexagonal InN films: correlation between strain and vibrational properties

The vibrational properties of InN films with different strain have been studied using Infrared ellipsometry and Raman scattering spectroscopy. We have established a correlation between the phonon mode parameters and the strain, which allows the determination of the deformation potentials and the strain-free frequencies of the InN E₁(TO) and E₂ modes. The LO phonons and their coupling to the free-carrier plasmon excitations are also discussed in relation to the carrier concentration in the films.     

Thermally induced optical bistability in PbTe at room temperature

Thermally induced optical bistability by continuous-wave CO₂ laser excitation is obtained for the first time in PbTe. Optical switching of the etalon atT=300K is achieved for input powers of tens of milliwatts. A theoretical analysis of the input-output characteristics is presented, where the temperature dependence of the free carrier absorption has been accounted for.