Cyclotron-phonon resonance power absorption in free standing nanostructure of transparent conducting oxides

Abstract

A theory of cyclotron-phonon resonance power absorption (CPRPA) in a free-standing nanostructure (FSNS) of transparent conducting oxides (TCO) is presented. An analytical expression for optical power absorption is obtained based on quantum mechanical perturbation technique for the case when electrons are scattered by bulk longitudinal polar optical phonons. The optical power absorption spectrum consists of a series of peaks due to electron transition between Landau levels with simultaneous absorption of photon and emission of phonon. The intensity and location of absorption peaks depends on the material parameters such as electron effective mass and LO-phonon energy. Frequency, temperature and thickness dependence of absorption power and the variation of full-width at half maximum (FWHM) of absorption peaks as a function of magnetic field, temperature, and number of Landau levels are presented. The FWHM of CPRPA peaks increases linearly with square root of magnetic field. Further, FWHM is independent of temperature and thickness of FSNS. The numerical results obtained for all TCOs confirm that CPRPA measurements would be useful in understanding optical absorption characteristics of TCOs in finite and zero magnetic fields.