Effects of cobalt thin films on the a-Si crystallisation induced by excimer laser irradiation

In the present work, we report the results obtained by laser irradiation of a-Si/Co/SiO2 and a-Si/SiO2 samples in order to study the influence of the Co film on the a-Si crystallisation process. Both Co and a-Si layers were d eposited by electron beam evaporation. Cobalt films of 0.5, 1 and 3 nm were deposited upon a 300 nm thick SiO2 layer. The thickness of the a-Si layer was fixed at 200 nm. Samples were irradiated by a XeCl excimer laser under fluences of 0.40, 0.45 and 0.50 J cm(-2) and 1 or 10 number of pulses. Graz ing incidence XRD and cross-sectional TEM were used for sample characterisa tion. Results showed the formation of CoSi2 that, in general, considerably improves the crystallinity of the a-Si layer. In some cases, the presence o f the CoSi2 underlayer allowed the complete crystallisation of the a-Si lay er even after the first laser pulse. Without CoSi2, the same results were o btained only with a higher number of pulses. (C) 1999 Published by Elsevier Science B.V. All rights reserved.