Precise nanosecond time resolved infrared radiometry measurements of laser induced silicon phase change and melting front propagation

Nanosecond laser melting of silicon was investigated by infrared (IR) radiometry and time resolved reflectivity (TRR) methods. IR radiometry revealed interesting signal evolutions and their qualitative changes during different stages of the melting process. The observed signals represent melting front propagation, liquid phase overheating, and melt duration. Comparison of IR and TRR methods is shown. The physical origin of the IR signal shapes is discussed in detail.