Instationary conjugate optical-thermal fields in thin films due to pulsed laser heating: A comparison between back and front treatment

Manufacturing of multilayer thin films deposited on a glass substrate can b e accomplished by means of pulsed laser sources. Thermal and optical nonlin earities are induced during transient heating, since the response of weakly absorbing thin films depends on the temperature. The heat source can eithe r directly impinge the film surface, front treatment, or the glass substrat e, back treatment. In this paper a one-dimensional conjugate non-linear the rmal-optical time dependent problem is numerically analysed. The investigat ion is accomplished in order to compare the two processes. For a Nd-YAG las er with wavelength of 1064 nm, a a-Si/TCO and Al/a-Si/TCO multilayers are i nvestigated. Results are presented in form of spatial and temporal temperat ure profiles as well as absorbed heat transfer rates inside the layers. The accomplished analysis clearly shows that the back treatment is more effici ent in terms of manufacturing process, oriented to the production of photov oltaic cells.