Date

2006

Author

Bilgi, Seda

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In this study, photoluminescence properties of as grown, Ge implanted GaSe and InSe crystals with doses 1013, 1014, and 1015 ions/cm2 and 1015 ions/cm2 Ge implanted and annealed GaSe and InSe single crystals grown by using 3-zone vertical Bridgman-Stockbarger system have been studied by photoluminescence spectroscopy (PL). PL spectra of as grown and implanted GaSe samples with three different doses have been studied in the ranges within the wavelength interval 570-850 nm and in the temperature ranges between 21 and 110 K. Temperature dependencies of all observed bands revealed that the peak with highest energy has excitonic origin and most of the others originate from donor-acceptor pair recombination. For GaSe samples implanted with 1013 and 1015 ions/cm2 Ge, PL spectra exhibited four emission bands while for as grown and the sample implanted with 1014 ions/cm2 v Ge had three bands. Variations of emission peaks were studied as a function of temperature. It was observed that centers of all bands shifted towards red continuously with temperature. The intensities of the emission peaks showed similarities with those obtained from as grown, 1013 and 1014 ions/cm2 Ge implanted GaSe while the peak intensities of the sample implanted with 1015 ions/cm2 Ge decreased with the temperature continuously. Using the temperature variation of the peak intensities and peak energy values activation energies were obtained and these results revealed that the two bands with low wavelength to be excitonic origin for the implanted samples with the doses 1013 and 1015 ions/cm2 Ge. Similar results were obtained for the implanted with 1015 ions/cm2 Ge and annealed sample. The other two peaks observed for these samples were attributed to donor acceptor pair transitions. In addition, direct band gaps were found to be 2.12 eV at 32 K for as grown, 2.121 eV at 25 K for 1013 ions/cm2 Ge implanted, 2.121 eV at 21 K for 1014 ions/cm2 Ge implanted, 2.124 eV at 33 K for 1015 ions/cm2 Ge implanted GaSe samples and lastly 2.113 eV at 28 K for 1015 ions/cm2 Ge implanted and annealed GaSe. PL spectra of as grown, 1013, 1014, 1015 ions/cm2 Ge implanted, and 1015 ion/cm2 Ge implanted and annealed InSe samples were also obtained at 20 K. Two broad bands were observed in the spectrum of all InSe crystals and considered to be due to impurity levels within the materials.

Subject Keywords

Spectroscopy.

URI

http://etd.lib.metu.edu.tr/upload/3/12607482/index.pdf
https://hdl.handle.net/11511/16412

Collections

Graduate School of Natural and Applied Sciences, Thesis