This SBIR Phase I project will demonstrate that high radiation-resistance can be elicited from nanostructured media comprised of semiconducting nanoparticles derived from size-governed wide band-gap CdTe or PbTe. In order to transform space-based particle sensors, nanocrystalline semiconductors provide an attractive material basis because they present a means of: 1) decreasing the underlying material cost by utilizing a solution-based fabrication methodology, 2) increasing the range of candidate materials by including the narrow-gap semiconductors, 3) increasing the exciton multiplicity upon the impingement of radiation by utilizing multi-exciton generation, and 4) increasing the radiation resistance because the introduction of a high density of nanoparticles can convey pronounced improvement in the radiation hardness of the material. In order to realize these properties, several experimental challenges must be overcome, the surmounting of which is one of the objects of the proposed research, during which we will: 1) utilize self-assembly to realize close-packed quantum-dot domains where the charge transport is optimized, and 2) extend the size of those domains to macroscopic size. The research is designed to not only deliver a high-performance radiation resistant sensor that can be commercialized but it will also advance basic physics by studying the interactions between energetic particles and strongly-confined charge carriers. By finding general material-design methods to suppress both radiation-induced damage and the stochastic thermal loss component in semiconductor materials, one can greatly increase the charge-conversion efficiency, which impacts the resolution of sensing devices, such as the particle detection application targeted, and the energy efficiency of energy harvesting materials, such as those used in solar-cells.
The higher spectroscopic performance in a radiation-hard package allows one to better correlate the solar particle emissions with the driving feature near the photosphere, thus helping to identify the origins and causes of the solar wind and the Sun’s magnetic field. Thus future NASA heliophysics missions will gain far greater specificity in mapping the solar-driven particles. Beyond heliophysics, fine energy resolution can be used to precisely characterize atmospheric and soil samples captured and ionized during planetary studies.
For the sensing of optical photons and nuclear radiation, the successful development of a low cost, high performance material will stand as a viable alternative to both single crystal semiconductors and scintillator-based detectors. Thus, optical cameras, medical imaging instruments, military radiation instruments, and rad-hard nuclear power would all be impacted by the successful development.