The field of the invention is high grade, II-VI semiconductor crystal growth using high-pressure hydrothermal processes and, in particular, growth of large Cadmium Telluride (CdTe) and Cadmium Zinc Telluride (CZT) crystals.
CdTe and CZT crystals have applicability for compact radiation detectors. CdTe and CZT detectors have been shown to exhibit good energy resolution, especially as compared to scintillator-based detectors. Since they are direct conversion devices, CdTe and CZT detectors eliminate the need for bulky photomultiplier tubes. Furthermore, CdTe and CZT detectors do not require cryogenic cooling as do high-purity germanium detectors.
CdTe and CZT crystals are conventionally grown by melting CdTe and CZT and allowing the melt to crystallize. Traveling heater systems, horizontal Bridgman, vertical Bridgman and high pressure Bridgman methods have been used to grow CdTe and CZT crystals from the melt or from the vapor phase. CdTe and CZT crystals grown by such melt and vapor phase processes tend to suffer from high cost and small crystal size. In addition, the crystals produced by these melt and vapor phase processes tend to have poor electrical and physical characteristics that greatly limit their sensitivity and application to economical radiation detectors. There is a long felt need for a robust technique for growing high purity, low-cost single CdTe and CZT crystals of a size suitable for high sensitivity detection at high resolution.
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