Radiation detection plays a vital role in countering weapons of mass destruction (WMD), interdicting nuclear threat, and nuclear attribution. Excellent energy resolution is crucial to distinguish real threat from natural background and nuisance sources. HPGe detectors are the current state-of-the-art high-resolution gamma spectrometers. However, their field deployment is often restricted due to high manufacturing and operating cost. Newly developed room-temperature semiconductor materials (e.g. CZT, HgI2) showed promising performance but normally come in limited sizes at high cost. Using nanofabrication techniques, this project aims to develop a new generation of room-temperature, high-resolution, large-volume radiation detectors based onnanocrystalline (NC) semiconductors. If successful, this effort could help promote widespread field deployment of high-resolution spectroscopy systems, which will undoubtedly improve the Nation’s capability to counter WMD, interdict nuclear threat and deter nuclear terrorism.

In NC materials, the quantum confinement effect leads to uniquely attractive properties, e.g. tunable band gap and carrier multiplication (CM) through impact ionization (II). While our previous study on NCs concentrated on lead chalcogenide and colloidal cadmium salt, thisproposed work will expand the search for NC materials with good uniformity and high charge carrier mobility. Exotic-shaped nanoparticles and nanostructures will be investigated to create more closely packed materials with better charge transport pathways. Chemical treatments that can potentially improve charge transport and enable simple yet effective deposition methods will be studied. We also aim to investigate and refine new device fabrication methods.