Annealing effects on structural, optical and electrical properties of e-beam evaporated CuIn 0.5 Ga 0.5 Te 2 thin films

Koray Yilmaz*, Hakan Karaagac

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

CuIn 0.5 Ga 0.5 Te 2 (CIGT) thin films have been prepared by e-beam evaporation from a single crystal powder synthesized by direct reaction of constituent elements in a stoichiometric proportion. Post-depositional annealing has been carried out at 300 and 350 °C. The compositions of the films were determined by energy dispersive X-ray analysis (EDXA) and it was found that there was a remarkable fluctuation in atomic percentage of the constituent elements following to the post-depositional annealing. X-ray diffraction analysis (XRD) has shown that as-grown films were amorphous in nature and turned into polycrystalline structure following to the annealing at 300 °C. The main peaks of CuIn 0.5 Ga 0.5 Te 2 and some minor peaks belonged to a binary phase Cu 2 Te appeared after annealing at 300 °C, whereas for the films annealed at 350 °C single phase of the CuIn 0.5 Ga 0.5 Te 2 chalcopyrite structure was observed with the preferred orientation along the (1 1 2) plane. The effect of annealing on and near surface regions has been studied using X-ray photoelectron spectroscopy (XPS). The results indicated that there was a considerable variation in surface composition following to the annealing process. The transmission and reflection measurements have been carried out in the wavelength range of 200-1100 nm. The absorption coefficients of the films were found to be in the order of 10 4 cm -1 and optical band gaps were determined as 1.39, 1.43 and 1.47 eV for as-grown and films annealed at 300 and 350 °C, respectively. The temperature dependent conductivity and photoconductivity measurements have been performed in the temperature range of -73 to 157 °C and the room temperature resistivities were found to be around 3.4 × 10 7 and 9.6 × 10 6 (Ω cm) for the as-grown and annealed films at 350 °C, respectively.

Original languageEnglish
Pages (from-to)6454-6458
Number of pages5
JournalApplied Surface Science
Volume256
Issue number21
DOIs
Publication statusPublished - 15 Aug 2010
Externally publishedYes

Keywords

  • Chalcopyrite compound
  • e-Beam evaporation
  • EDXA
  • X-ray diffraction
  • XPS

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