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In this work techniques for producing large uniform semi-insulating detector-grade CdTe crystals which are free of major structural defects (such as twins, non-uniform dislocation density, and precipitates) have been successfully developed. These p-type CdTe crystals have low carrier concentrations and resistivities of 10 8 -10 9 Ω cm. From such materials photo diodes as X-ray detectors can be designed with low leakage current, low capacitance, high speed, and high quantum efficiency.The use of CdTe for X-ray and gamma detection has been of interest because of its wide bandgap (1.5 eV), which would permit operation of such a device above room temperature, and because of its high atomic number (Z ≈ 50). The photoelectric cross-section is significantly larger than that for GaAs, Ge, and Si. Recently, there has been a great deal of interest in the use of room-temperature semiconductor X-ray detectors for application in medicine, biology, for X-ray non-destructive control and analysis, and in space physics with particular interest in detectors fabricated from CdTe. However, limitations in the charge transport properties and resistivity of the CdTe impose restrictions on its use in X-ray detectors. Furthermore, crystals of CdTe available today grown by the high-pressure Bridgman [1] and traveling heater [2] methods are not uniform in their defect structures and electric and physical properties. This imposes further restrictions on the design of X-ray detectors made from these materials.Nowadays, it is not certain which method of crystal growth is the most appropriate in obtaining large semi-insulating, uniform, and defect-free CdTe crystals. The properties of CdTe crystals used to construct large strip (or pixel) X-ray detectors for digital radiography must be such that the signal is large and does not vary with the pixel position. In the present work our effort is directed towards the growth of large-diameter uniform semi-insulating CdTe crystals required for the fabrication of X-ray imaging detectors. Preliminary results of the detector performance of (p-n) diode, X-ray detectors, fabricated on CdTe crystals are presented.Previously, the method of directed crystallization has been used for the growth of detector-grade CdTe crystals under a controlled pressure of cadmium with defect compensation by introducing Cl in melt [3]. In the present work we have used a variant of this method for the reproducible growth of large-diameter

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