Abstract
We demonstrate an effective method for fabricating large area periodic two-dimensional semiconductor nanostructures by means of single-pulse laser interference. Utilizing a pulsed nanosecond laser with a wavelength of 355 nm, precisely ordered square arrays of nanoholes with a periodicity of 300 nm were successfully obtained on UV photoresist and also directly via a resist-free process onto semiconductor wafers. We show improved uniformity using a beam-shaping system consisting of cylindrical lenses with which we can demonstrate highly regular arrays over hundreds of square micrometers. We propose that our novel observation of direct pattern transfer to GaAs is due to local congruent evaporation and subsequent droplet etching of the surface. The results show that single-pulse interference can provide a rapid and highly efficient route for the realization of wide-area periodic nanostructures on semiconductors and potentially on other engineering materials.
Highlights
Sub-micron periodic and quasi-periodic structures have shown enormous potential in the fields of nanophotonics [1,2], plasmonics [3,4], bioengineering [5], magnetic storage [6], nanofluidics [7], etc
We demonstrate an effective method for fabricating large area periodic two-dimensional semiconductor nanostructures by means of single-pulse laser interference
We propose that our novel observation of direct pattern transfer to GaAs is due to local congruent evaporation and subsequent droplet etching of the surface
Summary
Sub-micron periodic and quasi-periodic structures have shown enormous potential in the fields of nanophotonics [1,2], plasmonics [3,4], bioengineering [5], magnetic storage [6], nanofluidics [7], etc. We are about to report feature sizes down to sub-100 nm levels and a pattern pitch of 300 nm using our approach It would be advantageous as part of any fabrication process to dispense with the intermediate photoresist step and perform direct laser interference patterning (DLIP) [23,24,25] onto materials surfaces. Large incident angles are needed in order to obtain a small interference pitch and in this case the laser spot on the surface of the sample becomes highly elliptical due to the projection of the gaussian beam on the highly angled surface. We attribute the direct pattern formation on the GaAs wafer to surface decomposition followed by self-etching This approach shows the capability for direct, rapid and high-throughput patterning on semiconductor surfaces via single-pulse nanosecond laser interference, paving the way toward a single-step in-situ fabrication of semiconductor nanostructures
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