Metasurface Integrated Uncooled Silicon Germanium Oxide Microbolometers
Abstract
The proposed project will investigate the structure/property relationships for metasurface integrated uncooled microbolometers, specifically identifying the electromagnetic, thermal, and noise properties of the system as a function of the metasurface geometry and material selection. The goal is to understanding the tradeoffs and potential of the metasurface integrated microbolometer to dramatically improve performance of current technology in terms of achieving disruptively lower voltage noise power spectral density, high detectivity, while introducing spectral/polarization selectivity of the metasurface. This will allow for the resolution of IR radiation beyond just the intensity, adding new tools to improve existing performance, while minimizing cost. SixGeyO1-x-y will be used as the TCR semiconductor because it allows the refractive index as well as the electrical properties to be adjusted. The testbed of the project is to investigate technology capability for multi-spectral imaging applications. Statement of Objectives: We will pursue the following objectives: (1) Integrate SixGeyO1-x-y with metasurfaces, and study how the material properties are affected by the metasurfaces in order to understand the structure/stoichiometry relationships to electromagnetic/thermal/electrical properties and manufacturing cost. (2) Investigate SixGeyO1-x-y, with and without metasurface, to correlate the infrared optical constants, resistivity, TCR, voltage noise, density and specific heat with the stoichiometery of the material. (3) Fabricate and characterize an innovative uncooled IR microbolometer integrated with metasurface with a pixel area of 25?25 µm2 - 12?12 µm2 and a fill factor over 90% by placing support structure beneath the pixel. (4) Identify sources of noise and optimize combined system to further reduce noise in the fabricated devices. Statement of Approaches: A unified metasurface integrated microbolometer will replace the Fabry-Perot cavity/umbrella superstructure in traditional microbolomers. The metasurfaces will permit an engineered spectral/polarization selectivity while enhancing the electrical performance and minimizing the thermal mass of the microbolometer. This will allow improved thermal design because the support structure can be placed underneath the pixel without disrupting the resonant cavity. The presence of the metal metasurface elements has the potential to dramatically lower the resistivity of the microbolometer with slight improvement of the TCR. This goes well beyond the ordinary tradeoffs available for the Si-Ge-O system and corresponds to lowering the noise of the microbolometers without affecting sensitivity. Statement of Methods to be Employed: The proposed device will be fabricated using standard microfabrication processes, and scaled toward a 12?12 µm2 pixel size suspended above the substrate by thin metallic/dielectric arms. Using a metasurface will improve Si-Ge-O characteristics including IR absorptance, resistivity, TCR, and voltage noise. In addition, the deposition condition, and post deposition annealing will be investigated. Noise models will be created for reduction purposes. Novel low-cost microsphere photolithography approach will be used to realize metasurfaces with submicron dimensions and to provide a pathway to explore designs beyond what can be patterned with a basic mask aligner. Statement of Significance: The proposed devices can provide a low-cost multispectral capability with a broad range of applications in areas such as defeat camouflage, discriminate between natural/manmade surfaces, situational awareness, threat detection, surveying a battlefield to inspect for the use of chemical weapons or explosives before exposing US warfighters. Potential platforms include helmet-mounted sights, unmanned aerial vehicles, robots, and driverÕs aids for military vehicles.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 25, 2021
- Source ID
- W911NF2110072
Entities
People
- Mahmoud Almasri
Organizations
- Army Contracting Command
- United States Army
- University of Missouri