From Point Defects to Ripples: Ultrafast Laser Induced High Spatial Frequency Laser Induced Periodic Surface Structures.

Ultrafast Laser;Physics;Science;Materials Science and Engineering

Abere, Michael J.Torralva, Ben R. ;

University of Michigan

关键词: Ultrafast Laser;    Physics;    Science;    Materials Science and Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/116658/abere_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The interaction between multiple intense ultrashort laser pulses and solids universally produces a regular surface corrugation. We have identified a coupled mechanism that operates in a specific range of fluences in semiconductors between the band-gap collapse and ultrafast-melt thresholds that produces a unique corrugation known as high spatial frequency laser induced periodic surface structures (HSFL). The structures have period < 0.3 times the laser wavelength and are predominately epitaxial single crystal. HSFL formation is initiated when the intense laser field softens the interatomic binding potential, which leads to an ultrafast generation of point defects. The interplay between surface plasmon polaritons and transient surface morphologies driven by strain relaxation, via diffusing defects, localizes the point defect generation, which results in the evolution and eventual completion of HSFL formation. Changing the material and laser wavelength dependent surface plasmon polariton response allows for either control over the HSFL period or complete inhibition of their formation. Control over the HSFL formation mechanism opens the potential for ultrafast laser directed self-assembly.