SBIR-STTR Award

There is a need for low cost, high performance gamma-ray detectors for national and homeland security applications for detection, identification and localization of special nuclear materials. Common detectors used in this application include scintillators coupled to photomultiplier tubes or silicon photodiodes, and semiconductor detectors like cadmium zinc telluride. Semiconductor detector offer better energy resolution, lower power requirements and smaller size. However, despite decades of research and development the cost of CZT detectors remains high. To meet the needs of nuclear security a lower cost alternative with better properties is desirable. In recently there have been significant advances in heavy metal compound semiconductor halides like cesium lead perovskite and thallium bromide. There are numerous other semiconductor materials with the appropriate properties that may offer improved gamma-ray stopping power, lower noise and better energy resolution. In this effort, we will study and compare at least four new high atomic number materials selected based on average atomic number and semiconductor  bandgap. We will develop synthesis and crystal growth techniques, and fabricate and characterize detectors from each. Testing will be focused on sensitivity and spectroscopy. Based in the detection properties, the most promising material will be selected for further development and optimization Phase II.

Report developed under SBIR contract for topic NGA192-003 Advanced Materials and Algorithms for Radiation Detection. There is a need for low cost, high performance gamma-ray detectors for national and homeland security. There are numerous semiconductor materials with intrinsic properties that offer improvements in cost, gamma ray stopping power, lower noise and better energy resolution. In this effort, we are investigating semiconductor materials selected based on average atomic number and semiconductor bandgap. The goal of Phase I was to identify new detector materials to replace existing commercial materials. The Technical Objective were 1) Identify at least four semiconductors with the appropriate properties; 2) Grow crystals for evaluation; 3) Characterize the materials and demonstrate the potential to replace existing detector technologies. The goal and objectives have been successfully achieved. Phase II will optimize the synthesis, purification and growth of the materials. By the end of the first year, we will select the best of these for continued development. A major part of the second year will be developing and optimizing detectors. Configurations will include planar devices, pixelated devices, and position sensitive imaging devices. We anticipate that by the end of Phase II, we will have developed materials in which the performance and ease of growth will surpass that of existing detectors.