Applications of Laser Technology for Patterning, Modifying, and Thermal Effects on Substrates of Optoelectronic Materials

• Main Authors: Yu-Sen, Ho, 何友森
• Other Authors: Ming-Fei, Chen
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/22112189010876921198

博士 === 國立彰化師範大學 === 機電工程學系 === 99 === This thesis focuses on laser beam interaction with transparent conductive oxide (TCO) films on transparent substrates and a fundamental Nd: YAG laser processing system with 1064 nm wavelength. The laser processing system was applied to carve the electrode patterns of TCO films on transparent substrates according to the related process parameters, such as laser power, laser repetition rate, laser focusing position, and duration. In order to achieve high quality electrode patterns, the method for selecting a suitable set of parameters, by using laser direct writing technology, is important. Grey relational analysis is one of the forecasting analysis methods which can rapidly identify the optimum patterning parameters. Using the grey relational analysis optimizes the electrode patterns of laser process, including the sheet resistance and transmittance of the ITO/glass and ITO/PC substrates analysis to optimize performance characteristics. By analyzing the relation of the four factors, a set of optimal direct laser patterning parameters for ITO/glass and ITO/PC were obtained successfully. For the ITO/glass, the optimum machining parameters are: laser average power of 4 watt, laser repetition rate of 30 kHz, laser duration time of 600 , and laser focus at 1 mm below the substrate. For the ITO/PC, the optimum machining parameters are laser average power of 1.7 watt, laser repetition rate of 20 kHz, laser duration time of 300 , and laser focus at 1 mm below the substrate. For laser patterning on TCO films, the dot-scanning and vector-scanning methods in laser annealing on TCO films were discussed. Using beam shaping technology with symmetric intensity distribution enabled us to obtain a better surface roughness than using beam shaping technology with asymmetric intensity distribution. The electrical resistivity and carrier mobility of the TCO films could be improved by laser annealing treatment. The sheet resistance and surface roughness of as-deposited ITO films were 417 Ω/sq and 23 nm by laser annealing treatment with beam shaping with an inexpensive aperture instead of a beam shaper. After the laser annealing process, they were reduced to 400.4 Ω/sq and 4.2 nm. The sheet resistance and carrier mobility of as-deposited FTO films were 151.6 Ω/sq and 7.914 cm2/Vs, respectively. After the laser annealing process, they were reduced to 127.5 Ω/sq and 9.204 cm2/Vs, respectively. The electrical resistivity and carrier mobility of the TCO films can be improved by laser annealing treatment. Additionally, the flexible CIGS solar cells on the stainless steel substrate are also applied by using the laser technology with grey relational analysis and laser annealing technology. Some instruments are utilized in this paper, including the scanning electron microscope (SEM), x-ray diffraction (XRD), four-point probe, Hall-effect measurement, spectrophotometer, and atomic force microscopy (AFM).