Experimental realization of a well-controlled 3D silicon spiral photonic crystal

Abstract

Three-dimensional (3D) Si spiral photonic crystals have been realized by oblique angle deposition with a new approach of substrate 'swing' rotation. We demonstrate that, by using swing rotation, the arms of the spirals can be grown with a uniform diameter. Without swing rotation the arms of the spirals may overgrow due to a ballistic 'fan-out' phenomenon. The fabricated 3D Si spiral photonic crystals have a [0 0 1]-diamond symmetry which has been shown previously to have a large photonic band gap. Our optical measurements of reflectance have suggested the existence of such a photonic band gap in our structures centred at a wavelength of 2 µm.