Electrical and optical study of phase transitions in thermally evaporated GeTe films

P. Kumar, R. Thangaraj, T. S. Sathiaraj

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Amorphous to crystalline phase transformations in thermally evaporated GeTe films have been analyzed by using the resistivity-temperature curves and optical spectroscopic techniques. The phase-transition temperature increases slightly with annealing temperature, while a large change in the sheet resistance and appreciable decrease in the dc activation energy has been observed due to this transformation. The small value of sheet resistance for the crystalline films as compared to the amorphous ones above the transition temperature reveal the influence of the polarization near the metal/semiconductor interface forming the blocking layer at the interface toward the semiconductor side. The optical contrast value decreases with the decrease in wavelength due to the transitions from the deep levels below the valence band edge. The imaginary parts of dielectric function (ε 2) have been calculated from the reflectivity data using the Kramers-Kronig transformations and exhibit its strong dependence on the annealing temperature. The optical gap and tailing parameter have also been studied with annealing temperature. These results have been explained on the basis of the structural relaxation or the change in the local structure due to amorphous-crystalline transformation in the GeTe film due to thermal annealing.

Original languageEnglish
Pages (from-to)838-842
Number of pages5
JournalPhysica Status Solidi (A) Applications and Materials Science
Volume208
Issue number4
DOIs
Publication statusPublished - Apr 1 2011

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Phase transitions
Annealing
annealing
Sheet resistance
Superconducting transition temperature
transition temperature
Semiconductor materials
Crystalline materials
Temperature
Structural relaxation
temperature
Amorphization
Tailings
Electron transitions
Valence bands
phase transformations
Activation energy
Metals
Polarization
activation energy

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering
  • Materials Chemistry

Cite this

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Electrical and optical study of phase transitions in thermally evaporated GeTe films. / Kumar, P.; Thangaraj, R.; Sathiaraj, T. S.

In: Physica Status Solidi (A) Applications and Materials Science, Vol. 208, No. 4, 01.04.2011, p. 838-842.

Research output: Contribution to journalArticle

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AB - Amorphous to crystalline phase transformations in thermally evaporated GeTe films have been analyzed by using the resistivity-temperature curves and optical spectroscopic techniques. The phase-transition temperature increases slightly with annealing temperature, while a large change in the sheet resistance and appreciable decrease in the dc activation energy has been observed due to this transformation. The small value of sheet resistance for the crystalline films as compared to the amorphous ones above the transition temperature reveal the influence of the polarization near the metal/semiconductor interface forming the blocking layer at the interface toward the semiconductor side. The optical contrast value decreases with the decrease in wavelength due to the transitions from the deep levels below the valence band edge. The imaginary parts of dielectric function (ε 2) have been calculated from the reflectivity data using the Kramers-Kronig transformations and exhibit its strong dependence on the annealing temperature. The optical gap and tailing parameter have also been studied with annealing temperature. These results have been explained on the basis of the structural relaxation or the change in the local structure due to amorphous-crystalline transformation in the GeTe film due to thermal annealing.

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