Ordered arrays of micrometer- and nanometer-sized wells were fabricated by chemically etching an optical imaging fiber's distal face. Well depth was controlled by the etch reaction time. Well packi...

Ordered nanowell arrays

There is provided controlled fabrication of a solid state structural feature on a solid state structure by exposing the structure to a fabrication process environment the conditions of which are selected to produce a prespecified feature in the structure. A physical detection species is directed toward a designated structure location during process environment exposure of the structure, and the detection species is detected in a trajectory from traversal of the designated structure location, to indicate changing physical dimensions of the prespecified feature. The fabrication process environment is then controlled in response to the physical species detection to fabricate the structural feature. Also provided is a method for controlling a physical dimension of a structural feature or to form a feature by exposing the structure to a flux of ions at a selected structure temperature, the exposure conditions being controlled to cause formation of the feature or to cause at least one physical dimension of the feature to be changed, substantially by transport of material of the structure to the structural feature in response to the ion flux exposure.

Control of solid state dimensional features

Microchannel plate (MCP) event-counting imaging detectors with very high spatial resolution ( ∼ 10 μ m ) and timing accuracy ( ∼ 100 ps ) are widely employed for the detection and imaging applications of electrons and ions, as well as UV and X-ray photons. Recently, it was demonstrated that the many advantages of MCPs are also applicable to neutron detection with high two-dimensional spatial resolution. Boron, enriched in the isotope 10B, was added to the MCP glass structure to enhance the neutron interaction within the MCP through the B 10 ( n , α ) 7 Li reaction. The energetic charged particle reaction products release secondary electrons directly into MCP channels, initiating an electron avalanche and a subsequent strong output pulse. In this paper we present a detailed model for calculating the quantum detection efficiency of MCP neutron detectors incorporating 10B, for the specific case of square channel MCP geometry. This model predicts that for thermal neutrons (0.025 eV), MCP detection efficiencies of up to 78% are possible using square channels. We also show theoretically that square channel MCPs should have a very sharp ( ∼ 17 mrad ) angular drop in sensitivity for detection of normal incidence neutrons, opening up new possibilities for angle-sensitive neutron imaging as well as collimation. The calculations can be used to optimize MCP neutron detection efficiency for a variety of applications. In a subsequent companion paper, the model will be extended to the case of hexagonally packed circular channels.

/pdf/efficiency-optimization-of-microchannel-plate-mcp-neutron-3m85b2nrdl.pdf

Efficiency optimization of microchannel plate (MCP) neutron imaging detectors. I. Square channels with 10B doping

For controlling a physical dimension of a solid state structural feature, a solid state structure is provided, having a surface and having a structural feature. The structure is exposed to a first periodic flux of ions having a first exposure duty cycle characterized by a first ion exposure duration and a first nonexposure duration for the first duty cycle, and then at a second periodic flux of ions having a second exposure duty cycle characterized by a second ion exposure duration and a second nonexposure duration that is greater than the first nonexposure duration, for the second duty cycle, to cause transport, within the structure including the structure surface, of material of the structure to the structural feature in response to the ion flux exposure to change at least one physical dimension of the feature substantially by locally adding material of the structure to the feature.

Pulsed ion beam control of solid state features

Efficiency Optimization of Microchannel Plate (MCP) Neutron Imaging Detectors. I. Square Channels with 10B Doping

Secondary electron yield of SiO2 and Si3N4 thin films for continuous dynode electron multipliers

Substrates for microchannel plates have been fabricated using Si micromachining techniques. High aspect ratio pores are constructed using reactive ion etching and streaming electron cyclotron resonance etching, and low‐pressure chemical vapor deposition (LPCVD). In one process, 40 μm deep pores with 2 μm openings on 4 μm centers are directly etched in Si. Alternatively, pores with aspect ratios of 30:1 are constructed in a low‐stress SiNx membrane using a sacrificial template process whereby pillars of Si are etched and then subsequently backfilled with a dielectric using LPCVD.

Fabrication of high aspect ratio structures for microchannel plates

Dry etching of GaAs and fused silica for the production of microchannel plates is investigated. Etch methods used are magnetron reactive ion etching, chemically assisted ion beam etching (CAIBE), and electron cyclotron resonance etching (ECR). Extensive characterization of the ECR etcher is carried out with a designed experiment, which uses statistical methods to minimize the number of characterization runs. CAIBE gives high aspect ratio etching of GaAs, but at low etch rates. ECR provides higher etch rates of GaAs and better substrate temperature control. The effect of temperature on sidewall roughness and undercut is examined for temperatures as low as −100 °C. Features with an aspect ratio greater than 30 are presented. Etching of fused silica is difficult due to low etch rates (<0.2 μm/min), and faceting of the metal mask.

A. M. Then

Papers

Secondary electron yield of SiO2 and Si3N4 thin films for continuous dynode electron multipliers

Fabrication of high aspect ratio structures for microchannel plates

High aspect ratio dry etching for microchannel plates