Arradiance has developed active thin films, which hold the promise of revolutionizing microchannel plates (MCPs), channel electron multipliers, photomultiplier tubes and devices into which they are integrated, such as image intensifier (II) tubes used in night vision. These films possess specialized electrical properties that improve the functionality of state-of-the-art MCPs by significantly improving efficiency, noise, and lifetime performance.

Using advanced thin film deposition techniques and state-of–the-art materials characterization Arradiance has the capability to develop thin films with targeted electrical, mechanical and optical properties. Films developed for MCP application have been optimized for resistance and secondary electron emission in order to replicate and improve upon the behavior of the lead- glass film used by; current state-of-the-art MCP technology; a fiber optic-based technology fundamentally unchanged from the early 1970s. The functionality of the MCP relies upon an elevated temperature hydrogen reduction of the surface film to simultaneously form the electrically active resistive and secondary electron (SE) emissive layers. The lead-based glass system as presently used lacks the capability to independently optimize mechanical, resistive and emissive properties and also suffers from poor glass composition control that results in ion induced damage and lifetime degradation, Arradiance developed resistive and emissive films have demonstrated substrate independence and MCP performance improvements in gain (10x) and lifetime as a direct result of the ability to tailor all elements to maximize MCP performance.

Night vision - A typical image intensifying tube, used in night vision devices, is shown. In operation, light from the scene being viewed, which can be a low-level visible light and/or infrared light, is focused by the optical input element through the glass plate in the cathode window onto the photocathode. The photocathode converts the light striking it into electrons. The electrons travel into the MCP and are then multiplied. The resulting electrons strike the phosphor screen which converts the electrons into visible light.

A major drawback of the conventional image intensifying devices is that the electrostatic fields established in the II tube that transport the electrons from the photocathode coating to the MCP also transport positive ions present within the MCP back towards the photocathode. Because such positive ions can be of considerable size they are capable of causing physical and chemical damage to the photocathode. In order to counter these effects, state-of-the-art image intensifying devices use a thin ion barrier film on the input side of the MCP to block the ions from impacting or reacting with the photocathode. There are several drawbacks to the use of the ion barrier film:

1. Nearly a factor-of-two reduction in the signal-to-noise ratio of the device due to the absorption of secondary electrons by the ion barrier film.

2. The formation of a “halo” around the image, reducing image quality, due to:

• Photoelectrons incident on the ion barrier film which do not penetrate the ion barrier film and instead impact the film at another location.

• The physical distance between the photocathode and the front face of the MCP

3. Higher voltage must be applied between the photocathode and the MCP in order to overcome the electron barrier established by the ion barrier film.

Finally, the transmissive photocathode coatings used in state-of-the-art II tubes are difficult to optimized for efficiency in so far as they must be both thick enough so that photoelectrons are generated with high efficiency and thin enough for the photoelectrons to escape through the other side of the photocathode to the MCP, resulting in efficiency losses.

Replacing the MCP presently used in II devices with a device utilizing Arradiance thin film technology and eliminating the traditional ion barrier film has the following attributes:

• Reduced probability of photocathode poisoning due to the combined purity and barrier properties of the emissive film resulting in improved lifetime.

• Elimination of the image halo and vastly improved signal-to-noise

• Ability to target a wide dynamic range due to the ability to target device resistance over 7 orders of magnitude.

• high quantum efficiency performance due to the deposition of the photocathode onto the front face of the MCP

• Opportunity for higher levels of II integration resulting from the substrate independence of the Arradiance thin film technology.

Optical and Solar – The ability to precisely tune film parameters such as: thickness, barrier properties, conductivity, reflectivity, transmission and index of refraction, is critical for films used in the optical and solar industries. Arradiance has developed highly specialized nanoalloy and nanolaminate films which have the capability to tune mechanical, electrical and optical properties. A nanolaminate structure developed at Arradiance (figure right) comprised of a homogeneous thin film layered with a nanoalloy thin film that is capable of electrical resistance which spans 7 orders of magnitude. Arradiance has also developed several variants of Transparent Conducting Oxides (TCO), which are highly transparent and very conductive.

Nanotechnology and Biomedical – Film requirements broadly cover mechanical, electrical, optical and thermal properties. Arradiance has developed films which have the ability to conformably coat extremely high aspect ratio structures, such as the 300:1 capillary shown to the right, while retaining the ability to tailor film properties to the application. Such high aspect ratio coverage coupled with the demonstrated capability to functionalize thin films is directly applicable to chemical and biological sensor devices as well as micro fluidic, emulsification and semiconducting nanotube / nanowire coatings. Biomedical imaging devices, utilizing FLIM and FRET illumination, can benefit from the improved imaging provided by the advanced MCP devices developed using Arradiance thin film technology.

Scientific and Chemical – Analytical instrumentation used in scientific disciplines makes extensive use of charged particle detection devices for materials characterization. The MCP technology developed by Arradiance will significantly impact the analytic detection market, by improving performance (gain, sensitivity and noise) and device lifetime. Shown at right is the detection improvement resulting from Arradiance developed emissive layer for an astronomical detection device. Significant improvement in the pulse height distribution translates directly to improved detection capability. Chemical catalysis requires the use of substrates which possess ultra high surface area supports for catalytic reactions. Arradiance has demonstrated functionalized films, capable of high aspect ratio coverage which display angstrom level control over catalyst thickness and digital control of film stoichiometry.