Therefore, it is clear that deep nanopores with high aspect ratios are challenging to fabricate. The particular balance of parameters required for RIE is even dependent on the FIG. : SEM image of an easycleave sample showing 320 nm diameter apertures in the chromium mask and 2 different pitches, 600 nm (left) and 500 nm (right). The 84.5°angle between the photonic crystal axes is shown. After etching the sample is cleaved along the horizontal plane in this image to reveal the cross section for SEM imaging. The inset is a higher magnification image to better show the round apertures. diameter of the nanopores, so the etch process should ideally be optimised for the particular nanopores that are required in the final device.