The energy profile of polymorphous PbTe films. I. Direct energy gaps in PbTe high-pressure phases and energies of the heterophase junctions

Abstract

The transmittance and reflectance spectra of polymorphous PbTe films grown by laser-assisted deposition on KCl substrates were investigated in the range between 400 and 4000 cm-1. The refractive index dispersions n(E) were obtained from the spectra. The energy gaps Eg of the high-pressure (HP) PbTe phases were determined from the maxima in the dependences n(E)-Eg=0.23 eV for the BCC HP PbTe phase and Eg=0.42 eV for the orthorhombic HP PbTe phase. The additional maxima in the n(E) dependences were related to transitions across the heterophase junctions formed in the process of growth. The energy profiles of films grown under different technological conditions were obtained.