草場 光博

Abstract The surface morphology of silicon solar cells irradiated with KrF excimer laser pulses (λ = 248 nm, τ = 20 ns) was investigated below the experimentally observed melting threshold fluence (F _th) of 0.47 J cm⁻² (±20%). At laser fluences of 0.23–0.48 J cm⁻² (equivalent to 0.49F _th to 1.0F _th), nanodot structures with a height and width of approximately 60–120 nm were periodically formed with an interdot spacing similar to the laser wavelength. The observed nanodot density (29 dots μm²) was higher than that previously obtained at longer wavelengths. Furthermore, crystallinity analysis by micro-Raman spectroscopy revealed a Raman shift of 519.56 cm⁻¹ after irradiation (N= 1500 pulses), compared with 518.27 cm⁻¹ prior to irradiation. A laser fluence of 0.41 J cm⁻² ( = 0.87F _th) was found to induce compressive stress on the silicon solar cell surface.