(Color online) Schematic illustration of laser crystallization process on a-Si thin film: (a) As-deposited 400 nm a-Si on 100 nm SiO2 coated glass surface; (b) laser annealing of a-Si thin film; (c) nanodome structure formation after laser annealing; and (d) Secco etch to reveal the grain boundaries.
SEM images of (a) as-deposited a-Si and 400 nm thick a-Si thin films irradiated under different laser energy densities, (b) 266 mJ/cm2, (d) 294 mJ/cm2, (e) 380 mJ/cm2, (f) 439 mJ/cm2.
SEM image of a-Si film irradiated under the optimal laser condition of energy density of 380 mJ/cm2, repetition rate of 20 kHz and scanning speed of 20 mm/s after Secco etch.
(Color online) Raman spectra of 400 nm thick a-Si thin films irradiated with laser energy densities: 294 mJ/cm2, 380 mJ/cm2, 439 mJ/cm2, and 507 mJ/cm2 with intensity peak around 520 cm−1. The inset shows the Raman spectrum of the original as-deposited a-Si film, with the peak at ∼480 cm−1.
(Color online) Surface morphologies of (a) original as-deposited planar 400 nm thick a-Si thin film with a roughness of 3.4 nm and (b) UV laser irradiated film with laser energy density 380 mJ/cm2. The AFM scan area is 5 μm × 5 μm.
(Color online) (a) Reflection, (b) transmission, and (c) absorption spectra of laser treated 400 nm thick a-Si thin films with laser energy densities of 294 mJ/cm2, 380 mJ/cm2, 439 mJ/cm2, and 507 mJ/cm2. (d) Absorption spectra of the a-Si thin film with thickness of 100 nm. The original as-deposited planar 400 nm a-Si is used as a reference.
(Color online) Absorption spectra of (i) experimental 400 nm thick a-Si thin film irradiated with laser pulse energy 380 mJ/cm2and (ii) simulated Si nanodome structure with a periodicity of 300 nm and 400 nm. The dome height is 300 nm and the underlying film is 100 nm. The inset gives the simulated periodical nanodome structure.
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