Optical Properties of Te-Based Chalcogenide Alloys in the Mid- and Far Infrared Regions

Abstract

Ternary telluride alloys of GeSe(Sb)Te and SiGe(Ga)Te systems are synthesized in glassy and crystalline states for use in the terahertz frequency range. The transmission spectra of the obtained alloys are measured and studied in a wide wavelength range from 0.75 to 300 ?m. The possible mechanisms of their formation are discussed. A comparative analysis of the results shows that the Ge₁₄Sb₂₈Te₅₆ alloy of the GST system is most promising. Its phonon spectrum is in the range of 40280 cm¹, limiting the long-wavelength transmission window of this alloy by 35 ?m. Optimization of the Ge₁₄Sb₂₈Te₅₆ composition, the removal of impurities, and heat treatment will promote a further decrease in the absorbance in the far-infrared spectrum of this alloy.