Colloidal self-assembly as a versatile tool for direct writing of three-dimensional silicon-based photonic lattices.
(2011) MRS 2011 Spring Meeting — Location: San Francisco (USA) (25.April.2011)
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- Abstract
- In this talk, the fabrication and characterization of 3D silicon photonic lattices using colloidal sphere nanolithography is presented. Ordered monolayers arrays of polystyrene micro- and nano-particles fabricated using interfacial self-assembly have been explored with respect to that. The hexagonal packing has been mainly employed due to its simplicity and reliability in large area fabrication. The exploration and realization nanospheres square arrangements induced by the shape of the meniscus at the edges of the silicon substrates has been tested as well. The colloidal templates have been either used as such or subsequently modified to fabricate aluminum hard-masks for the deep reactive ion etching of silicon (DRIE). A single-step etch protocol was developed in order to generate periodic diameter modulated self-aligned nanochannels in silicon. The method is based on the standard Bosch silicon DRIE protocol with subsequent improvements in order to precisely design and adjust the period and the size of the etch modulations. The principle relies on consecutive surface passivation and etch steps using C4F8 and SF6 plasma chemistries respectively. The diffusion of fresh reacting and etch product species into the etched channels was found to play an important role affecting the structural uniformity of the fabricated structures. The diffusion induced etch rate drift was corrected by adjusting the reaction times. The optimized protocols were used to fabricate various 3D nanostructures in silicon. Ordered arrays of diameter modulated post or porous architectures have been successfully realized by adding the third dimension to the 2D colloidal crystal assemblies through the developed DRIE protocol. Delamination of silicon nanostructured stacks or kinked nanowires can be also realized by carefully adjusting the balance between the deposition and etch steps. Finally, we demonstrate the realization of the 3D photonic crystal quality lattices exhibiting optical band-gaps in the infrared spectral region proving the potential of the respective technique for fast, simple and large-scale fabrication of photonic structures [1].
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Dutu, C. A., Jedrasik, P., Södervall, U., Melinte, S., & Vlad, A. (2011). Colloidal self-assembly as a versatile tool for direct writing of three-dimensional silicon-based photonic lattices. MRS 2011 Spring Meeting, San Francisco (USA). https://hdl.handle.net/2078.5/224925