Diode Laser Crystallization of Hydrogenated Amorphous Silicon Thin Films for Solar Cell Applications

Abstract

The research objectives were to prove the crystallization of hydrogenated amorphous silicon (a-Si:H) thin films using a diode laser operating at an 805 nm wavelength and to provide morphology trends in laser crystallized samples. This work was primarily intended for solar cell applications. One industry goal was to produce a high-efficiency and low-cost solar cell capable of competing economically with other energy sources at large scale in the world market. Excimer laser crystallization was one very promising technique. However, two important problems still hindered economic competition. This research addressed the problems associated with excimer laser crystallization by utilizing a diode laser which provided an increased absorption depth in the silicon layer and dramatically reduced the cost. Results from x-ray diffraction measurements proved the presence of crystalline silicon after laser treatment. Optical microscope pictures of laser scanned samples were obtained, categorized by surface morphology, and entered into a matrix according to testing conditions. Trends were noticed and morphology predictions were performed.