Focused ion beam milling of three dimensional nanostructures with high precision

The fabrication of an extended three-dimensional nanostructure with dimensions much larger than the feature size using a focused ion beam is described. By milling two identical patterns of pores with a designed diameter of 460 nm in orthogonal directions, a photonic crystal with an inverse woodpile structure was made in a gallium phosphide single crystal. The patterns are aligned with an unprecedented accuracy of 30 nm with respect to each other. The influence of GaP redeposition on the depth, shape, and size of the pores is described. The work is published in J. Vac. Sci. Technol. B [1]

Fabrication of an active nanostencil with integrated microshutters

An active nanostencil, consisting of a thin (200 nm) silicon nitride membrane with attached polysilicon microactuators that can be used to dynamically open and/or close holes in the silicon nitride membrane, is presented. This nanostencil can be used as a shadow mask in an evaporation setup. Main features of the nanostencil are the absence of sacrificial oxide in the final product, strengthening of the membrane by a polysilicon hexagonal structure that is attached directly to the membrane and the use of low-doped regions in the polysilicon to separate the stator and rotor electrically

Electrochemical Formation of Porous GaP in Aqueous HNO3

Porous gallium phosphide was produced by anodic etching of n-type GaP in an aqueous solution of 1 M HNO3. At potentials lower than 15.5 V, yellow porous samples were obtained, of which the pore size was around 45% larger than the pores obtained in 0.5 M H2SO4. At potentials around 15.5 V electropolishing occurred. No pores formed when GaP was etched at potentials in this range. At potentials higher than approximately 15.5 V the current density increased strongly with increasing potential, and very large pores formed. It was found that NO₃^- and SO₄^2- only play a role in the chemical dissolution of the oxide layer that forms during etching

Fabrication of three-dimensional nanostructures by focused ion beam milling

The fabrication of an extended three-dimensional nanostructure with dimensions much larger than the feature size using a focused ion beam is described. By milling two identical patterns of pores with a designed diameter of 460 nm in orthogonal directions, a photonic crystal with an inverse woodpile structure was made in a gallium phosphide single crystal. The patterns are aligned with an unprecedented accuracy of 30 nm with respect to each other. The influence of GaP redeposition on the depth, shape, and size of the pores is described. A literature study revealed that the redeposition of GaP during milling is more pronounced than that of Si found in previous studies. An explanation for this phenomenon is given

The influence of fabrication deviations on the photonic band gap of three-dimensional inverse woodpile nanostructures

The effects of unintended deviations from ideal inverse woodpile photonic crystals on the photonic band gap are discussed. Such deviations occur during the nanofabrication of the crystal. By computational analyses it is shown that the band gap of this type of crystal is robust to most types of deviations that relate to the radii, position, and angular alignment of the pores. However, the photonic band gap is very sensitive to tapering of the pores, i.e., conically shaped pores instead of cylindrical pores. To obtain three-dimensional inverse woodpile photonic crystals with a large volume, our work shows that with modern fabrication performances, reduction in tapering contributes most significantly to a high photonic strength