[12p-B410-1~16] 3.7 Laser processing

△ [12p-B410-15] Conditions for fine LIPSS formation induced with mid-infrared FEL for semiconductors – Thresholds of LIPSS formation and melting -

〇(M1C)Yohei Tanaka¹, Chikai Hosokawa¹, Masaki Hashida^1,2, Heishun Zen³, Takeshi Nagashima⁴, Norimasa Ozaki⁵, Shunsuke Inoue^1,2, Shuji Sakabe^1,2 (1.GSS, Kyoto Univ., 2.ICR, Kyoto Univ., 3.IAE, Kyoto Univ., 4.Setsunan Univ., 5.GSE, Kyoto Univ.)

Keywords:laser induced periodic surface structures, mid-IR free electron laser, semiconductor

In-situ observation is an effective way to clarify the formation mechanism of laser induced periodic surface structures (LIPSS). However, the periodic space of fine LIPSS is about 1/10 of the laser wavelength so too small to be observed with visible laser light probes. We have proposed to use the LIPSS of larger interspace produced with infrared free electron laser (IR-FEL) for the observation of the formation process. As a preliminary experiment we have investigated experimentally the irradiation conditions for the LIPSS formation on semiconductors with mid-IR-FEL. It has been found that the LIPSS can be formed on the semiconductor of which laser-fluence threshold of LIPSS formation is smaller than that of melting.