Optimization of periodic column growth in glancing angle deposition for photonic crystal fabrication

摘要

We investigate the growth of periodically aligned silicon microstructures for the fabrication of square spiral photonic crystals using the glancing angle deposition phi-sweEP 4process. We report the optimization of the phi-sweEP 4offset angle for fabrication of microstructures with more precise geometry. The effects of varying the sweEP 4offset angle of the phi-sweEP 4process are studied for films deposited onto a square lattice array of growth seeds. To represent one growth segment of the phi-sweEP 4process, we fabricate 15 nm silicon thin films using several azimuthal substrate offsets from 0 degrees to 45 degrees at a vapor incidence angle of 85 degrees. We also deposit silicon square spirals on square lattice arrays with the phi-sweep method, using various sweEP 4offset angles from gamma = 0 degrees to 45 degrees. We find that using an offset angle of gamma = 26.5 degrees optimizes the shadowing geometry, which minimizes anisotropic broadening, producing greater quality photonic crystal structures. From normal incidence reflection spectroscopy, a maximum full width at half-maximum of 273 +/- 3 nm and a relative peak width (Delta lambda/lambda) of 16.1 +/- 0.1% were found for a sweEP 4offset angle of gamma = 26.5 degrees.