Theoretical and experimental studies of a-Si:H recrystallization by XeCl excimer laser irradiation

Studies of phase transitions in amorphous hydrogenated silicon (a-Si:H) thick films (2–4 μm) caused by XeCl laser irradiation, with the pulse energy density above the melting threshold of a-Si:H but below the threshold of monocrystalline silicon (c-Si), are presented. A mathematical model of non-equilibrium phase changes, including crystallization in the solid state, is formulated. Time-resolved reflectivity (TRR) measurements are performed to monitor the appearance and time evolution of various phases during the irradiation. The final structure is studied using scanning electron microscopy (SEM). The theoretical and experimental results are analyzed from the point of view of the polycrystalline silicon (pc-Si) grain size, and the sequence of the phase changes during the irradiation is found. The theoretical simulation is in good agreement with the experimental observations as well as with the data previously published by other authors.