Characterization and FDTD simulation analysis on light trapping structures of amorphous silicon thin films by laser irradiation

• The light trapping structures of α-Si thin film are formed by pulsed laser irradiation.
• Different reflection spectra corresponding to h/D are obtained by FDTD simulation.
• Reflection spectra with different structure are measured by UV–visible spectroscopy.
• The morphology characterization verifies light-trapping modeling in the simulation.

The effect of laser energy density on the light-trapping structures of amorphous silicon (α-Si) thin films is studied both theoretically and experimentally. The thin films are irradiated by a frequency-doubled (λ = 532 nm) Nd:YAG pulsed nanosecond laser. An effective finite difference time domain (FDTD) model is built to find the optimized laser energy density (EL) for the light trapping structures of α-Si. Based on the simulation analysis, it shows the variation of reflection spectra with laser energy density. The optimized reflection spectra at EL = 1000 mJ/cm2 measured by UV–visible spectroscopy confirms to agree well with that corresponding to the depth to diameter ratio (h/D) in the FDTD simulation. The surface morphology characterization by optical microscope (OM) and scanning electron microscope (SEM) accords fairly well to of light-trapping modeling in the simulation.

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