단일 펨토초 레이저펄스를 이용한 실리콘 표면에서의 시분해 반사율 측정 연구

Time-resolved transient reflective image on silicon surface after single-shot fs-laser pulse irradiation

In this work, we have studied on time-resolved transient reflective image of single crystalline Si surface after single-shot fs-laser irradiation with varying the laser fluence under two different laser spot sizes. The temporal profiles of transient reflectivity changes as well as its maximum values at the early delay time were found to be strongly dependent on both the laser beam spot size and laser fluence. We have interpreted the dependence of transient reflectivity changes on the laser spot size in terms of a relaxation of the generated free carriers to the bulk silicon, which should be interacted with the plasma.