Developing CZT for Single Element Spectrometers

Large volume CdZnTe gamma ray detectors would improve radiation detection capabilities in support of the nonproliferation of nuclear weapons. However, scientific and commercial interest in large volume CdZnTe gamma-ray detectors has been obstructed by a lack of consistent, high-quality crystalline substrates. Intrinsic limitations of the material have been well studied, and by using a variety of device structures and electronic techniques to compensate, CdZnTe detectors have shown superior performance over scintillators in many applications. At this time, further detector improvement is limited by the current crystal growth process for CdZnTe. As an alternative to the conventional technique, this project will grow CdZnTe crystals by the solvent flux method, otherwise known as the traveling heater method (THM). This method, which has provided consistent yields of CdTe substrates for many years, has specific properties that could overcome the exact problems facing CdZnTe production. Detector-grade CdTe crystals have been produced by the THM method for many years, and the technology to will be adapted to CdZnTe. Phase I will examine modifications to the technique. Following several crystal growth runs, the resulting material will be analyzed for electrical, physical, and chemical properties. Commercial Applications and other Benefits as described by the awardee: A steady supply of high quality CdZnTe detector material should make a variety of large volume and large area gamma ray detectors commercially viable. In addition to applications to nonproliferation and homeland security, these compact detectors should be well suited for dosimetry applications and as high performance counters for monitoring hazardous locations and materials. Finally, numerous applications within medicine could take advantage of higher performing detectors for better imaging quality and the quantification of radiopharmaceuticals