Improvement of the Productivity in the THM Growth of CdTe Single Crystal as Nuclear Radiation Detector

The effect of the THM growth rate on the CdTe crystalline quality and the detector performance was intensively investigated. The maximum growth rate for the single crystal growth was found to be approximately 15 mm/day which was 3 times greater than the conventional one. By optimizing other growth conditions, 90% of every ingot volume has become a single crystal. Te inclusions in the CdTe single crystal grown at various growth rates were also investigated by IR transmission microscopy. There was no correlation between the behavior of Te inclusions and the growth rate. The detector performance was also independent of the growth rate. Taking advantage of the large volume CdTe single crystals, about 700 000 Schottky detectors with 4 mm × 7.5 mm × 1 mm were fabricated for the research and development of the new positron emission tomography (PET) system using CdTe detectors. The average FWHM for the 662 keV line from ¹³⁷Cs and its standard deviation were 2.24% and 0.48%, respectively. This uniformity was essential for the development of the new PET system.