A pilot investigation on laser annealing for thin-film solar cells: Crystallinity and optical properties of laser-annealed CdTe thin films by using an 808-nm diode laser
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- Kim, N., Park, C.I. & Park, J. Journal of the Korean Physical Society (2013) 62: 502. doi:10.3938/jkps.62.502
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Compared to conventional furnace and rapid thermal annealing, laser annealing for heterojunctioned thin-film solar cells has several advantages including excellent annealing selectivity to the under-layers with a localized high temperature for a short process time. A continuous wave 808-nm diode laser was used for the laser annealing process of CdTe thin films for various output powers. The grains in the laser-annealed CdTe thin films grew along the C (111), H (110), and C (311) planes. Laser annealing resulted in an increase in grain size and a decrease in surface roughness. The optical band gap energy of the CdTe thin films was affected directly by the grain size, showing 1.460 eV and 1.415 eV for the as-deposited and laser-annealed CdTe thin films, respectively. The absorbance of the CdTe thin films with better crystallinity showed an improved value of 99.5–99.9% in the visible spectral region after laser annealing at an output power of 0.91 W.