Structural and compositional investigations of vapour grown CdTe:Cr single crystals

Highly doped CdTe:Cr single crystals were grown by the modified physical vapour transport method from pre-synthesized charge with 2.5 and 5 at% of chromium in the initial feed. Complex investigations of their structure and composition were performed by means of scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and secondary ion mass-spectroscopy techniques. It was revealed that the grown crystals contain Cr-Te-related particles arised in consequence of phase separation due to exceeding of chromium solubility limit in cadmium telluride. Besides, in the crystal grown from the nominally higher doped ingot there appear Te inclusions and void originated from the presence of Te-rich solutions on the growth interface. Formation mechanism of the observed structural imperfections during growth process was addressed. Concentration of Cr atoms, incorporated into the host matrix of vapour grown CdTe crystals, was found to be about 0.1 at%.