Macroporous silicon with a complete two-dimensional photonic band gap centered at 5 μm

TLDR

A triangular lattice of circular air rods with a 2.3‑µm lattice constant was etched 75 µm deep into n‑type silicon by electrochemical pore formation in HF, then micromechanically structured to leave 200‑µm‑thick free‑standing porous bars that were used to measure the lattice transmission. The fabricated two‑dimensional photonic crystal exhibited a complete band gap for both polarizations centered at 5 µm, with experimental transmission spectra matching theoretical predictions.

Abstract

We have fabricated a two-dimensional photonic band structure based on macroporous silicon with a gap common to both polarizations and centered at 5 μm. A triangular lattice of circular air rods with a lattice constant of 2.3 μm was etched 75 μm deep in an n-type silicon substrate by electrochemical pore formation in hydrofluoric acid. The porous layer was then micromechanically structured in such a way that 200 μm thick free-standing bars of porous material were left over on the silicon substrate. These bars were then used for measuring the transmission of the photonic lattice. The results showed an excellent agreement with the theoretically calculated structure.