GaSe thin films were deposited by thermal evaporation technique with and
without Cd doping. X-ray analysis showed that the crystallinity increases in (1014) preferred orientation direction with annealing for doped and undoped films. The room temperature conductivity and mobility values of the samples were found to be for doped and undoped films in between 1.3× / 101 - 3.4× / 102 (& / #8486 / -cm)-1, 1.2× / 10-6 - 1.5× / 10-6 (& / #8486 / -cm)-1 and 5.9 & / #8211 / 20.9 (cm2/V.s) (for doped samples only), respectively.
Due to the high resistivity of the undoped samples mobility measurements could not be performed. The dominant conduction mechanisms were determined to be thermionic emission in the high temperature region (250-400 K), tunneling in the range 160-250 K and between 100-150 K variable range hopping mechanism for the
doped films. For the undoped films above 250 K thermionic emission was the
dominant conduction mechanism. Space charge limited currents in parallel and
perpendicular directions of the film surface showed two different localized energy levels with different concentrations for each case, namely, 99.8 meV with concentration 3.5× / 1012 cm-3 and 418.3 meV with the concentration 2.2× / 105 cm-3 for
parallel direction and for perpendicular direction 58.3 meV with concentration
6.2× / 1025 cm-3 and 486.1 meV with concentration 3.3× / 1022 cm-3. Photocurrentillumination
intensity dependences indicated that power exponent of illumination
intensity with values n> / 1 implied two recombination centers exist in studied
samples.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/4/1085240/index.pdf |
| Date | 01 January 2003 |
| Creators | Colakoglu, Tahir |
| Contributors | Parlak, Mehmet |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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