Modification of electrical properties of zinc oxide by continuous wave ytterbium fiber laser irradiation

Abstract

The polycrystalline plate-like ZnO samples were irradiated by a continuous wave Yb fiber laser and electrical properties of modified layer were investigated. The laser beam of spot size of 16 μm in diameter was scanned on the surface at a velocity of 5mm/s. There was a threshold for the laser modification. The laser etched grooves were formed above laser power of 20 W. The laser etched depth increased in relation to the laser power, 0.46 mm at 20 W and 5.0 mm at 126 W. The surface layers of laser etched grooves were modified in color and electrical property. The color changed from light yellow to black, and the electrical resistivity drastically decreased from initial value of 1.1×105 Ωcm to 3.2×10−1 Ωcm at 56 W, 2.8×10−1 Ωcm at 91 W, and 2.0×10−1 Ωcm at 126 W. The Hall measurement showed that the modified surface layer was an n-type semiconductor and carrier concentration of the layer was 1.5×1017 cm−3 at 56 W, 7.2×1017 cm−3 at 91 W, and 1.9×1018 cm−3 at 126 W.