Direct observation of ultra-rapid solid phase crystallization of amorphous silicon films irradiated by micro-thermal-plasma-jet

Abstract

This paper presents a new method to directly observe the transient evolution of amorphous silicon temperature and the solid phase crystallization during micro-thermal-plasma-jet irradiation. Using the time-resolved reflectivity analysis, nucleation temperature and characteristic crystallization time were determined. When the heating rate increases from 4.45×105to 2.28×106K/s, the nucleation temperature increases from 985 to 1071 °C. The characteristic crystallization time decreases from 95 to 20 μs with an increase in heating rate. Crystallization time as a function of temperature corresponds to the activation energy of 2.9 eV. This energy relates to both the nucleation and growth process. Micro-Raman spectroscopy results indicate that the crystalline volume fraction of solid–phase crystallized Si film is higher than 65 %, and it increases to 80 % with decreasing scanning speed. Both high resolution transmission electron microscopy results and theoretical calculation indicate that there is a distribution of final crystal size. The average grain size is smaller than 50 nm and depends on the annealing conditions, namely the faster heating rate is, the smaller grain size is.