High spatial frequency laser induced periodic surface structure formation in germanium by mid-IR femtosecond pulses
Abstract
Formation of high spatial frequency laser induced periodic surface structures (HSFL) in germanium by 90 fs mid-IR pulses at a 1 kHz repetition rate with wavelengths between λ = 2 and 3.6 μm was studied with varying angle of incidence and polarization. The period of these structures varied from λ/3 to λ/8. A modified surface-scattering model including Drude excitation and the optical Kerr effect explains the spatial period scaling of HSFL across the mid-IR wavelengths. Transmission electron microscopy shows the presence of a 30 nm amorphous layer above the structure of crystalline germanium. Various mechanisms including two photon absorption and defect-induced amorphization are discussed as probable causes for the formation of this layer.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Oct 12, 2016
- Source ID
- 10.1063/1.4964737
Entities
People
- Allen Y. Yi
- Cosmin I. Blaga
- Drake. R. Austin
- Enam Chowdhury
- Hui Li
- Kaikai Zhang
- Kyle R. P. Kafka
- Louis F. DiMauro
- Yu Hang Lai
- Zhou Wang
Organizations
- Air Force Office of Scientific Research
- Air Force Research Laboratory
- Ohio State University