ИСТИНА

Femtosecond laser pulses with high emission intensity and low photon energy can help to achieve uniform nanostructuring and modification over the entire volume of siliceous films [1], as well as anisotropy of their structural, electrical and optical properties. For example, surface periodic structures can be formed [2]. Femtosecond laser radiation also can be used to improve the properties of amorphous hydrogenated silicon films (a-Si:H) for potential applications in photovoltaics. In this paper, a-Si:H films were processed by femtosecond laser pulses (1250 nm, 100 fs, spot diameter 150 μm) in raster mode. Scanning electron microscopy revealed the presence of the one-dimensional grating-like structure with a period of about 0.36±0.03 or 1.11±0.05 μm on the treated surface, perpendicular to polarization of the incident beam. This result is in agreement with the data of [3]. Electrical measurements have shown that the conductivity of a-Si:H film after irradiation with femtosecond laser pulses increased up to 3 orders of magnitude due to dehydrogenation and nanocrystallization of the film [4]. The conductivity along the scan lines and periodic structures is almost threefold greater than in the perpendicular direction. This effect can be explained by non-uniform crystallization of amorphous silicon, and the electric field anisotropic depolarization inside the surface periodic structure. [1] A. V. Emelyanov, M. V. Khenkin, A. G. Kazanskii, et al. Thin Solid Films 410–413 (2014) 556 [2] G.A. Martsinovsky, G.D. Shandybina, Yu.S. Dementeva et al. Semiconductors 1339–1345 (2009) 43 [3] R. Drevinskas, M. Beresna, M. Gecevičius et al. Appl. Phys. Letters 171106 (2015) 106 [4] A.V. Emelyanov, A.G. Kazanskii, P.K. Kashkarov et al. Semiconductors 769–774 (2012) 46