Enhancement of band gap and photoconductivity in gamma indium selenide due to swift heavy ion irradiation
- Department of Physics, Cochin University of Science and Technology, Cochin 682022 (India)
{gamma}-In{sub 2}Se{sub 3} thin films prepared at different annealing temperatures ranging from 100 to 400 deg. C were irradiated using 90 MeV Si ions with a fluence of 2x10{sup 13} ions/cm{sup 2}. X-ray diffraction analysis proved that there is no considerable variation in structural properties of the films due to the swift heavy ion irradiation. However, photosensitivity and sheet resistance of the samples increased due to irradiation. It was observed that the sample, which had negative photoconductivity, exhibited positive photoconductivity, after irradiation. The negative photoconductivity was due to the combined effect of trapping of photoexcited electrons, at traps 1.42 and 1.26 eV, above the valence band along with destruction of the minority carriers, created during illumination, through recombination. Photoluminescence study revealed that the emission was due to the transition to a recombination center, which was 180 meV above the valence band. Optical absorption study proved that the defects present at 1.42 and 1.26 eV were annealed out by the ion beam irradiation. This allowed photoexcited carriers to reach conduction band, which resulted in positive photoconductivity. Optical absorption study also revealed that the band gap of the material could be increased by ion beam irradiation. The sample prepared at 400 deg. C had a band gap of 2 eV and this increased to 2.8 eV, after irradiation. The increase in optical band gap was attributed to the annihilation of localized defect bands, near the conduction and valence band edges, on irradiation. Thus, by ion beam irradiation, one could enhance photosensitivity as well as the optical band gap of {gamma}-In{sub 2}Se{sub 3}, making the material suitable for applications such as window layer in solar cells.
- OSTI ID:
- 21064517
- Journal Information:
- Journal of Applied Physics, Vol. 103, Issue 2; Other Information: DOI: 10.1063/1.2829812; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ABSORPTION
ANNEALING
HEAVY IONS
ILLUMINANCE
INDIUM SELENIDES
ION BEAMS
MEV RANGE 10-100
MEV RANGE 100-1000
PHOTOCONDUCTIVITY
PHOTOLUMINESCENCE
PHOTOSENSITIVITY
RECOMBINATION
SEMICONDUCTOR MATERIALS
SILICON IONS
SOLAR CELLS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
THIN FILMS
X-RAY DIFFRACTION