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We propose a new and promising technique to study quantum-size structures. In ultrathin monocrystalline PbTe films with thicknesses L=6, 18, and 30 nm, we have examined this technique, based on two-photon optical excitation of the renormalized electronic structure and revealed a sharp dependence of frequencies of two-photon resonant transitions on L. We explained this result within the framework of a model taking into account the real PbTe band structure, electron–electron and electron–phonon interactions, and interband and intra band redistribution of free carriers. We have estimated the characteristic time of interband polarization decay as T2≥300 fs and have analyzed the transformation of the nonlinear response for the case L→∞.

The possibilities and advantages of tJV-laser ablation technique for deposition of doped PbTe thin films are discussed. To understand the effects of experimental parameters on layer formation the stages of laser sputtering of the target and film growth were investigated. Method of laser ionization RETOF mass spectrometrv was used to obtain the energy distribution and chemical nature of evaporated particles as a function of wavelength and laser radiation power. The influence of cxperimental parameters on the deposited film thickness stoichiometry and crystalline perfection was checked. The dependence of doped PbTe films photoelectrical properties on the experimental parameters.O-8194-1082-9/93/$6.OO Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/16/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx SPIE Vol. 1856 Laser Radiation Photophysics (1993) /47 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/16/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

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