Damage and Micropattem Formation in Ge-Sb-Te Phase Change Materials Induced by Intense Terahertz Pulse Train

Intense terahertz radiation is promising for material control and understanding of the THz-matter interactions is important research topic. We irradiated Ge-Sb- Te phase change material thin films with a train of THz pulses from a free electron laser and found that the surface changes that are damage as a precursor to ablation and the undulations were induced without amorphization. The undulation pattern is thought to be a sort of laser induced periodic structure (LIPSS) that is one of important phenomena in the field of laser material processing. Absence of amorphization implies that photo- or electrical-excitation plays an important role for fast phase change operation.