This project addresses science and technology of a new materials system comprising nanoscale islands - quantum dots - embedded in a thin semiconductor film. The electronic and optical properties of the materials are designed to enable ultrafast detection of x-rays and energetic quantum particles. The key element of this sensing material is a light-emitting quantum dot ensemble capable of converting energy from incoming x-rays into infrared light. This type of material performance, known as scintillation, is carried out with unsurpassed energetic yield and speed, thus providing a long-expected solution for key technological applications. Such ultrafast x-ray detection is essential for implementing low-dose x-ray three-dimensional medical imaging, as in computer or positron-emission tomography (PET), as well as for improving accuracy and turnaround time in nuclear systems security. The project enables technology development and commercialization, potentially facilitating the emergence of higher quality medical and defense instrumentation at reduced cost. The educational component of the project includes direct support of a graduate student research assistant towards a Ph.D. in nanoscale engineering, hands-on training of undergraduate students, launching a new optical nanomaterials laboratory segment for K-12 students, and training of science teachers within the educational College infrastructure.
relatively weak existing material interactions at high energies lead to a fundamental challenge for picosecond-scale timing of energetic particles and photons. A large-volume scintillation medium coupled to a small and fast photodetector is the preferable approach to remedy this limitation, where the time response is limited by the excitation transfer and emission, as well as the optical transit time. This project develops a new scientific approach and technology for a scintillation material using quantum dots as nano-engineered emission centers capable of providing unsurpassed speed and light yield, additionally exploring detector integration in order to test the performance benefits. While the concept is not material-specific, the current technology level and the required device properties favor self-assembled InAs quantum dots (QDs) embedded in a GaAs waveguide as the test material system. The project includes a modeling component, engineering and fabrication of QD waveguides with an integrated photodetector, and assessment of time and energy resolution. This study paves a path for enabling reduced radiation doses in medical 3D imaging/tomography applications, improving spectroscopic accuracy in nuclear security, and enhancing particle identification capabilities in high-energy physics experiments. The project enables technology development and commercialization efforts, promotion of nanotechnology to the broader public, additionally enriching the College outreach infrastructure.
