ИСТИНА

Femtosecond laser pulses with high emission intensity and low photon energy can be used for uniform modification of a-Si:H films [1] and to achieve anisotropy of their structural, electrical and optical properties. For example, surface periodic structures (ripples) can be produced [2]. In this paper, a-Si:H films treated by femtosecond laser pulses (1250 nm, 100 fs) were investigated. A surface profile with period equal to the laser spot diameter (150 mkm) was formed by means of laser beam movement in the raster mode. Scanning electron microscopy also revealed presence of one-dimensional periodic structure, perpendicular to polarization of the incident beam on the treated surface, with 0.36±0.03 μm period. The electric conductivity of a-Si:H film after irradiation with femtosecond laser pulses increases by almost 3 orders of magnitude due to dehydrogenation and nanocrystallization of the film [3]. Due to non-uniform crystallization of amorphous silicon and the electric field depolarization by periodic structure, the conductivity along the scan lines and periodic structures is almost threefold greater than in the perpendicular. The work was financially supported by the Russian Foundation for Basic Research (project 16-32-80066). [1] A. V. Emelyanov, M. V. Khenkin, A. G. Kazanskii, et al. Thin Solid Films 556, 410 (2014) [2] R. Drevinskas, M. Beresna, M. Gecevičius et al. Appl. Phys. Letters 106, 171106 (2015) [3] A.V. Emelyanov, A.G. Kazanskii, P.K. Kashkarov et al. Semiconductors 46, 769 (2012)