| CdSe, a II -VI compound with direct transition, wide-band-gap and high atomic number (48,34), is regarded as a new effective materials for room temperature nuclear radiation detectors and photoconductive devices.In our study, the technique of the purification of start materials and the single crystal growth had been improved. Purification of the polycrystalline and growth of CdSe single crystals were carried on in the same quartz ampoule. The start materials could be transferred into the growth ampoule directly in the last process of purification, which avoided the extra contamination. CdSe single crystals with high quality were grown by modified growth method, i.e. vertical unseeded vapor growth with multi-step purification. The as-grown crystal was characterized by using x-ray diffraction, IR tansmission, etdi pit density, SEM and other analysis techniques. It was found that the magnitude of as-grown crystals resistivity was about 10 7-10 8 Q .cm, the magnitude of electron trap densities was about 108 cm-3 and the IR transmittance of the crystal sample was about 40% in the range from 7000 cm-1 to 350cm-1. The etch pit patterns of (110) face of CdSe crystals were also reported firstly and the magnitude of dislocation densities was about 104cm-2. Detectors, which were fabricated with as-grown CdSe single crystals, obtained the resolution of 23KeV for 59.5KeV 241Am Y -ray at room temperature. The results show that the modified growth technique is a new and promising method for growing highly pure and perfect CdSe single crystals .This work is an important part of the chief scientific and technological subjects sponsored by the Ministry of Education of China. It will be significant not only for the further study of CdSe single crystals but for the practical applications of the crystals.
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