Ripples formation on the silicon solar cells surface by laser irradiation

Abstract

The surface and electric properties of the monocrystalline silicon solar cell treated by means of focused light from a 20-ns-pulsed YAG:Nd3x laser (A = 1.064 pm) at repetition rate of 12.5 Hz have been investigated. The laser beam was focused down to spot size of 1.2 x 0.04 mm2 by means of optical condenser consisting of spherical and cylindrical lenses onto surface of the solar cell in the area between two nearest contacts of the contact grid. Optical beam power was used in a sequence of 0.14 mW, 0.35 mW, 0.44 mW, 0.48 mW, 0.52 mW and 0.76 mW. The reference and laser treated samples cut from a single solar cell have been investigated experimentally by measuring current-voltage characteristics in dark and under illumination by a 5000 K Xenon lamp. Laser fluence greater than 4.5 mW/mm2 per pulse forms ripples on the sample surface along the length of the laser beam spot and repetitive along the beam scanning directions. The results of our electric measurements and images taken by optical microscope are presented and discussed.