Miniaturized High-Speed Modulated X-Ray Source (MXS)

The SQDIX system is an enabling technology that will have game-changing impacts across many fields including DoE, DoD, NASA, medical imaging fields, aircraft inspection and many other fields. StQDs are sensitive to x-ray radiation and emit visible photons that are tunable in wavelength. Development of this technology will greatly impact NASAs ability to use X-Rays as an inspection method. This directly addresses the Aviation Safety challenge in the 2010 National Aeronautics R&D Plan to monitor and assess the health of aircraft more efficiently and effectively as well as all NASA spaceflights beyond earths magnetic field.

Conventional scintillation radiation detectors make use of materials that emit light when hit by ionizing radiation. These large, bulky scintillators range anywhere from 6 inches to 6 feet in size. They are attached to glass photomultiplier tubes (PMTs), which are fragile, require high voltages, and are extremely sensitive to temperature changes. Conventional detectors also include a wave shifter (a material with a dopant to re-emit the scintillator light to match the sensitivity of the PMT or photodiode) which reduces efficiency and introduces unwanted weight and bulk. Glenn's particle counter overcomes these challenges. A prototype was constructed from off-the-shelf components, and features a small scintillator (less than six inches long) and a low-voltage, UV-sensitive, wide-bandgap photodiode as the detector. Careful matching of the properties of the light emitted from the scintillator, and tailoring the sensitivity of the photodiode eliminates the need for a PMT and a wave shifter, not only saving space, weight, and power but also eliminating potential failure modes. By using wide-bandgap detectors, it can operate in changing temperature, vibration, pressure, and gravity conditions without need for a temperature compensation system. Built from solid-state components, Glenn's device is compact and robust.

This technology is a method of using x-ray diffraction (XRD) to evaluate the concentration of crystal structure defects, and thus the quality, of cubic (100)-oriented semiconductor wafers. Developed to enhance NASA's capabilities in fabricating chips for aeronautics applications, the method supplants existing methods that not only destroy the wafer in question, but can take as long as a day to determine the quality of a single wafer. The approach can be used with any commonly used semiconductor, including silicon, SiGe, GaAs and others, in a cubic (100) orientation, which covers at least 90% of commercial wafers. It can also be used to evaluate the quality of epi layers deposited on wafer substrates, and of ingots before they are sliced into wafers.

The Phononic Isolated KID Fabrication Process utilizes a silicon on insulator, or a silicon wafer coated with a thin film bilayer of silicon oxide and silicon nitride (or amorphous silicon), to be used as the starting wafer. The silicon or silicon nitride thin films act as the structural material. The films thicknesses are chosen based on the desirable phononic crystal properties. The phononic crystal is patterned with electron beam lithography to get minimum features. The structures are etched in a fluorine plasma chemistry stopping on the oxide layer. The niobium or other superconductor layer is deposited, patterned, and etched. This can be done in a liftoff process so as not to damage the SiN or Si underlayer. A hafnium or other superconductor is deposited, patterned, and etched to function as the kinetic inductance material. A silicon handle wafer is patterned and etched using deep reactive ion etching which stops on the silicon oxide. The silicon oxide is etched in hydroflouric acid and a wax bonding material used as a temporary bonding material is dissolved. The final structure is removed from the temporary handle wafer. This process is beneficial in that it is simple aside from the incorporation of the nanostructured membranes. The Phononic Isolated KID Fabrication Process is an implementation of incorporation of a phononic crystal into a KID architecture. The process can also incorporate a second dieletric material such as nanocrystalline diamond that can be used as a stiffening material for the phononic crystal.

In many applications, such as remote sensing of atmospheric trace gases, monochromatic radiation with multiple discrete wavelengths is required. Yet to date, there no instrument or technique that measures the wavelength jitters and fluctuations in real-time. This novel technique provides simple and accurate real time wavelength monitoring by obtaining two independent measurements using two different wavelength-dependent conditions to solve for both radiation power and wavelength simultaneously. These conditions could include operating a single detection system at different settings as well as using two different detection systems. The technique requires initial calibration for the detection systems being used, specifically around the expected detection wavelength.