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Suwon, South Korea

Do W.,Hongik University | Jin W.-B.,Hongik University | Choi J.,Hongik University | Bae S.-M.,Hongik University | And 4 more authors.
Materials Research Bulletin | Year: 2014

Boron-implanted polycrystalline Si thin films on glass substrates were subjected to a short duration (1 ms) of intense visible light irradiation generated via a high-powered Xe arc lamp. The disordered Si atomic structure absorbs the intense visible light resulting from flash lamp annealing. The subsequent rapid heating results in the electrical activation of boron-implanted Si thin films, which is empirically observed using Hall measurements. The electrical activation is verified by the observed increase in the crystalline component of the Si structures resulting in higher transmittance. The feasibility of flash lamp annealing has also been demonstrated via a theoretical thermal prediction, indicating that the flash lamp annealing is applicable to low-temperature polycrystalline Si thin films. © 2014 Elsevier Ltd. Source

Hwang J.-H.,Hongik University | Kim H.J.,Hongik University | Kim B.-K.,Viatron Technologies | Jin W.-B.,Hongik University | And 3 more authors.
International Journal of Thermal Sciences | Year: 2015

Applying an in-line Xe-arc flash lamp annealing (FLA) process for the fabrication of low-temperature polycrystalline silicon (LTPS) on a large-scale glass substrate, this study investigates the effects of scanning multishot irradiations on the thermo-mechanical deformation of the substrate and the microscopic phase-change of the amorphous silicon (a-Si) thin-film. A glass substrate with thin-film structures was preheated at 650 °C, exposed to sequential multiple flashes, and thus heated rapidly far beyond the glass softening temperature to achieve crystallization of a-Si. Temperature variations in the substrate were predicted by one-dimensional heat conduction model with radiation absorption, and the structural deformations were simulated through a FEM code and compared to the experimental observations. The maximum temperatures arisen in the substrate during the second or subsequent flash irradiations were substantially lower than that during the first irradiation owing to reduced absorptions of flash energies. These absorption reductions were resulted from phase-changes of silicon from amorphous to polycrystalline. Those temperatures, however, were still sufficiently high to cause a significant thermal warpage, resulting in the bathtub shape of the substrate. The critical mechanisms for the warpage were the structural shrinkage and the gravitational sagging. In addition, the microscopic structural characteristics of the LTPS fabricated by the scanning multishot FLA process were explored through optical and Raman spectroscopies, and transmission electron microscopy. © 2015 Elsevier Masson SAS. Source

Kim D.-H.,Hongik University | Kim B.-K.,Viatron Technologies | Kim H.J.,Hongik University | Park S.,Hongik University
Thin Solid Films | Year: 2012

Experimental and theoretical investigations on flash lamp annealing (FLA) of amorphous silicon (a-Si) film on glass were carried out with a view to practical applications in large-window display industries. A Xe arc flash lamp of 950 mm in length and 22 mm in bore diameter was applied with nominal input voltage of 7 kV and flash duration of 400 μs. Prior to the annealing process, the specimen for FLA was preheated at 650°C, which was very close to the service temperature of the glass specimen used in this study. By employing a focusing elliptic reflector, maximum light energy density of up to 8.4 J/cm 2 could be attained with an active exposure width of 2 cm. Crystallization of a-Si could be achieved in solid-phase by applying a flash beam with light density of at least 5 J/cm 2, and its phase-transition characteristics that varied with energy densities could be explained by theoretically estimated temperature fields. Electron microscopy observations confirmed that solid-phase crystallization preceded melting of a-Si due to relatively long flashing (heating) duration of 400 μs, which was comparable to solid-phase crystal-growth times at elevated temperatures. © 2012 Elsevier B.V. All rights reserved. Source

Kim Y.,Hongik University | Park S.,Hongik University | Kim B.-K.,Viatron Technologies | Kim H.J.,Hongik University | Hwang J.-H.,Hongik University
International Journal of Heat and Mass Transfer | Year: 2015

Abstract Using a Xe-arc flashing of 0.4 ms, indium tin oxide (ITO) thin-films widely applied to fabricate transparent conducting electrodes for solar cells and displays are annealed at room temperature in order to improve their electric conductance and optical transmittances. ITO thin-films of 100 nm in thickness are deposited on a glass substrate of 500 μm in thickness by the magnetron sputtering method. Ray-tracing calculation estimates that heat absorbed in the thin-film during flash lamp annealing (FLA) process with using an additional back-reflector increases by about 2.8 times greater than that without using the back-reflector. Simulation based on one-dimensional conduction/radiation heat transfer model shows that the film temperatures during the FLA process exceed the crystallization point of the ITO material, indicating that its physical properties have been varied accordingly. Undergoing the short experimental FLA process, resistivity of the specimen has been decreased by about 30%, which is comparable to the ones obtained from conventional furnace annealing at temperatures ranging 200-300 °C for an hour, while the transmittances in the visible light range have been slightly increased. Morphological features of the films are investigated using XRD, XPS, AFM, and SEM, indicating that the specimens treated by the FLA or in furnace have crystallites larger than that of the as-received. © 2015 Elsevier Ltd Source

Kim D.H.,Hongik University | Kim D.H.,Viatron Technologies | Kim B.-K.,Hongik University | Kim H.J.,Hongik University
Transactions of the Korean Society of Mechanical Engineers, B | Year: 2012

The flash lamp annealing (FLA) process has been considered highly promising for manufacturing lowtemperature polysilicon on large-scale backplanes. Based on a theoretical estimation, this study clarifies the critical mechanisms of glass backplane deformation during the FLA process. A simulation using a commercial FEM code with viscoelastic models shows that the local region, whose temperature is larger than the glass softening point, undergoes permanent structural shrinkage owing to stress relaxation. For larger backplanes (4th Gen), structural shrinkages and gravitational deflection are critical to deformation in the FLA process, resulting in an "M" shape; in smaller backplanes (0th Gen), the latter is negligible, resulting in a "U" shape. © 2011 The Korean Society of Mechanical Engineers. Source

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