Study of the refractive index change in a-Si:H thin films patterned by 532 nm laser radiation for photovoltaic applications

• Published in: Thin solid films 2010-07, Vol.518 (18), p.5331-5339
• Main Authors: Colina, M., Molpeceres, C., Holgado, M., Gandia, J., Nos, O., Ocaña, J.L.
• Format: Article
• Language: English
• Subjects: Aparells i accessoris; Applied sciences; Bateries solars; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Energia solar; Energia solar fotovoltaica; Energies; Energy; Enginyeria electrònica; Exact sciences and technology; Hydrogenated amorphous silicon; IR-VIS spectroscopy; Laser deposition; Laser scribing; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Natural energy; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Photovoltaic cells; Photovoltaic conversion; Photovoltaic power generation; Physics; Raman spectroscopy; Silicones; Solar cells; Solar cells. Photoelectrochemical cells; Solar energy; Thin films; Àrees temàtiques de la UPC
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2010.04.016

Laser scribing of hydrogenated amorphous silicon (a-Si:H) is a crucial step in the fabrication of thin film photovoltaic modules. During such process, inherent thermo-mechanical effects associated to laser ablation mechanisms lead to thermal damages. In that sense, the state of the material remaining in the vicinity of the ablated area has a critical influence on the electrical properties of the final devices. In this work, a comprehensive analysis of refractive index variations for the material surrounding the ablated area by means of Infrared–Visible Fourier transform spectrometry is proposed. Besides, in order to evaluate the material microstructure, Raman spectroscopy is employed as a complimentary technique. It was seen that the refractive index variation decreased as the distance from the center of the ablated groove was increased. Likewise, a clear transition from highly crystalline to amorphous material could be also observed as a function of the distance from the groove.