Crystallization of silicon films of submicron thickness by blue-multi-laser-diode annealing

Blue-Multi-Laser-Diode Annealing (BLDA) was performed in the continuous wave (CW) mode on Si films as thick as 0.5 μm and 1 μm deposited by rf sputtering. As a result of controlling the laser power from 4.0 to 4.8 W, a whole Si layer of 0.5 μm in thickness was completely crystallized and consisted of a columnar structure of fine grains beneath a partially melted Si surface owing to the high temperature gradient along the depth in the Si layer. After additional hydrogenation in a furnace ambient, the ratio of the photo/dark current under AM1.5 illumination distinctly improved to 6 times higher than that of as-deposited condition. The BLDA is expected to be applied to thin-film solar cells and/or to thin film transistor (TFT) photo-sensor systems on panels as a new low-temperature poly-silicon (LTPS) fabrication technique.

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