Abstract: Elements of photonic devices with high aspect ratio patterns are fabricated. A stabilizing catalyst that forms a stable metal-semiconductor alloy allows to etch a substrate in vertical direction even at very low oxidant concentration without external bias or magnetic field. A metal layer on the substrate reacts with the oxidant contained in air and catalyzes the semiconductor etching by the etchant. Air in continuous flow at the metal layer allows to maintain constant the oxidant concentration in proximity of the metal layer. The process can continue for a long time in order to form very high aspect ratio structures in the order of 10,000:1. Once the etched semiconductor structure is formed, the continuous air flow supports the reactant species diffusing through the etched semiconductor structure to maintain a uniform etching rate. The continuous air flow supports the diffusion of reaction by-products to avoid poisoning of the etching reaction.

Abstract: Elements of photonic devices with high aspect ratio patterns are fabricated. A stabilizing catalyst that forms a stable metal-semiconductor alloy allows to etch a substrate in vertical direction even at very low oxidant concentration without external bias or magnetic field. A metal layer on the substrate reacts with the oxidant contained in air and catalyzes the semiconductor etching by the etchant. Air in continuous flow at the metal layer allows to maintain constant the oxidant concentration in proximity of the metal layer. The process can continue for a long time in order to form very high aspect ratio structures in the order of 10,000:1. Once the etched semiconductor structure is formed, the continuous air flow supports the reactant species diffusing through the etched semiconductor structure to maintain a uniform etching rate. The continuous air flow supports the diffusion of reaction by-products to avoid poisoning of the etching reaction.

Abstract: X-ray scattering imaging can provide complementary information about the unresolved microstructures of a sample. The scattering signal can be accessed with various methods based on coherent illumination, which span from self-imaging to speckle scanning. The directional sensitivity of the existing methods is limited to a few directions on the imaging plane and it requires the scanning of the optical components, or the rotation of either the sample or the imaging setup, if the full range of possible scattering directions is desired. A new arrangement is provided that allows the simultaneous acquisition of the scattering images in all possible directions in a single shot. This is achieved by a specialized phase grating and a device for recording the generated interference fringe with sufficient spatial resolution. The technique decouples the sample dark-field signal with the sample orientation, which can be crucial for medical and industrial applications.

Abstract: X-ray scattering imaging can provide complementary information about the unresolved microstructures of a sample. The scattering signal can be accessed with various methods based on coherent illumination, which span from self-imaging to speckle scanning. The directional sensitivity of the existing methods is limited to a few directions on the imaging plane and it requires the scanning of the optical components, or the rotation of either the sample or the imaging setup, if the full range of possible scattering directions is desired. A new arrangement is provided that allows the simultaneous acquisition of the scattering images in all possible directions in a single shot. This is achieved by a specialized phase grating and a device for recording the generated interference fringe with sufficient spatial resolution. The technique decouples the sample dark-field signal with the sample orientation, which can be crucial for medical and industrial applications.