LASER INDUCED IMPLANTATION DOPING OF GLASS SUBSTRATES

摘要

Lasers are widely used as high-accuracy tools for material processing. Different types of lasers such as CO_2, Nd:YAG, and excimer lasers are used in different operating modes such as continuous wave, pulsed or Q-switched. Volumes of materials and their composition, structure, and properties can be controlled or modified by varying laser pulses. In this research, by using laser as a material processing tool, an experimental method was developed for laser induced implantation doping of glass substrates with conductive metals. Experiments were performed on glass samples using Q-switched Nd:YAG lasers. Gold, silver, and copper were used as conductive dopant materials. Initial experiments were performed using nickel as a catalyst. Effect of the catalyst on the composition of implanted dopant material was observed using Large Area Rapid Imaging Analytical Tool (LARIAT). Through further experiment, the effect of several parameters such as beam fluence, scanning speed, pulse repetition frequency, wavelength, substrate temperature, dopant material, and glass substrate material on the morphology of heat affected zones were investigated by optical microscopy (OM). Depth of penetration in doped glass samples was measured for different substrate temperatures by means of a laser displacement sensor. The effect of beam fluence and glass substrate thickness on depth of penetration was investigated. The results of these nondestructive measurements were verified using scanning electron microscopy (SEM). Based on optical observations, morphological characteristics of the heat affected zone were assessed in order to obtain the best parameter settings in different experiments. These settings were defined by factors such as the number and size of cracks in glass substrates, and the quality of the distribution of dopant metal over the scanned pattern. While using a catalyst with substrates at room temperature, the best parameter settings were obtained at wavelength of 532 nm, pulse repetition frequency of 6 kHz, beam fluence of 0.36 J/cm~2, and scanning speed of 0.10 m/s. By removing the catalyst, these settings were changed to 355 nm, 10 kHz, 0.09 J/cm~2, and 0.01 m/s for gold sputtered soda-lime glass substrate at 500 °C. For beam fluence values ranging from 0.06 J/cm~2 to 0.38 J/cm~2, the obtained values for average depth of penetration were 255 μm and 187 μm in 1 mm and 3 mm thick soda-lime glass substrates respectively. Further development of this implantation method could lead to implantation of electronic circuits in transparent substrates, inspiring the evolution of transparent electronic devices such as transparent smart phones, smart windows and displays, and lighting products in the future.