Development of Cadmium Magnesium Telluride for Picosecond Response X-Ray Optical Laser Photodetector

The constantly improved and upgraded X-ray Free Electron Lasers (FEL) have been opening the doors for many scientific frontiers in biology, chemistry and material science, such as structural dynamics, matter at extreme conditions and nanostructure imaging. Incision structural probes, such as sub-picosecond time- resolved x-ray spectroscopy and diffraction, time-resolving chemical reactions, femtosecond X-ray/optical cross- correlation diagnostics, and the associated synchronization of the FEL with separate optical lasers are keys to these sciences. However, the lack of suitable ultrafast detectors covering X-rays to Vis-NIR has been preventing/limiting such studies. The Hamamatsu G4176-03 ultrafast Metal-Semiconductor-Metal (MSM) photodetector, which is GaAs- based, is a potential solution, but was recently discontinued. A replacement with equivalent or better performance is thus needed as currently called for by the DOE. Brimrose Technology Corporation proposes the development of a picosecond photodetector based on Cadmium Magnesium Telluride (CdMgTe) single crystal that is sensitive to both optical and x-ray pulses for coarse timing in Free Electron Laser Applications. Our goal is to successfully produce a photodetector based on in-house grown CdMgTe that has potential of exhibiting better detector performance, while having similar form factor/packaging to the Hamamatsu G4176-03 ultra-fast MSM photodetector. Brimrose can achieve this goal using our vast experience and expertise in II-VI materials technology, including CdMgTe. Recently, our collaborator on this subject, Prof. Roman Sobolewski of the University of Rochester (UR), NY, has demonstrated that Brimrose grown CdMgTe has exhibited sub-picosecond optical response to femtosecond laser pulses and would also be very sensitive to picosecond x-ray pulses, as well. We now would like to continue our CdMgTe photodetector development effort, to optimize its performance, as well as develop the recipe for reliability and commercial scalability. The combination of Brimrose and UR forms a strong team with vast experience in photodetector materials growth, expertise in fabricating proposed devices, pertinent characterization facilities and commercialization experience, promising success to meet the objectives of the proposed program. The successful outcome of this Phase 1 research is a CdMgTe photodetector that has similar form factor/packaging and performance equal to or better than that of the Hamamatsu G4176-03 Ultrafast MSM photodetector, thus enabling the coarse timing in FEL applications. Subsequently, all applications that rely on ultrafast timing of FEL, such as femtosecond X-ray/optical cross-correlation diagnostics, will benefit, especially in biology, chemistry and material science. Hence, there is a tremendous potential for widespread commercialization of the materials and devices that will be developed during this program. Additionally, at this time, ultrafast Cd1-xMgxTe photodetector materials are not available commercially. We hope to develop a domestic source for this material as an outcome of this research. We feel that our expertise in commercialization can make this a reality.