Origin of nonlinear optical characteristics of crystalline Ge-Sb-Te thin films for possible superresolution effects

Hyun Seok Lee, Byung Ki Cheong, Taek Sung Lee, Jeung Hyun Jeong, Suyoun Lee, Won Mok Kim, Donghwan Kim

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An experiment was conducted to investigate the origin of the nonlinear optical characteristics of crystalline Ge2Sb2Te 5 and Ge-doped SbTe thin films which have been demonstrated to have the capability of a superresolution readout. By means of the real-time measurement of the electrical resistance combined with concurrent optical reflectance/transmittance measurement during pulsed laser irradiation of varying power, it was found that the absorption coefficients of these films decrease with increasing laser power, accompanied most probably by an increase in the carrier concentration. This finding may be understood in light of the saturable absorption due to band filling by thermally assisted photoexcited carriers. This has been previously proposed as an important cause of the superresolution effect of PbTe, which belongs to the chalcogenide degenerate semiconductors such as the GeSbTe materials under study.

Original languageEnglish
JournalJapanese Journal of Applied Physics, Part 2: Letters
Issue number12-16
Publication statusPublished - 2007 Apr 13



  • Free carrier
  • Ge-doped SbTe
  • GeSb Te
  • Nonlinear optical effect
  • Optical data storage
  • PbTe
  • Saturable absorption
  • Superresolution (SR)

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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