Traveling heater method growth and characterization of CdMnTe crystals for radiation detectors

In this paper, the Cd_0.9Mn_0.1Te (CdMnTe) crystals were grown by the self-designed Traveling Heater Method (THM) crystal growth system. Two types of polycrystalline CdMnTe feed ingots synthesized in a traditional rocking furnace and in a vertical Bridgman furnace were adopted during the THM growth, and the as-grown crystals were denominated as CMT1 and CMT2, respectively. The crystal and detector properties, including the Te inclusions, Mn composition, PL spectrum, electrical and energy response properties were characterized. The results showed that the CMT2 ingot had less Te inclusion and more uniform Mn composition distribution along the ingot than CMT1 ingot. During the THM growth, the polycrystalline feed material synthesized by VB technique favoured a smooth and low concave growth interface, which decreased the formation of Te inclusions and Mn variation in the ingot. The resistivity of the CdMnTe crystal grown by THM was in the range of (0.5-4) x 10¹⁰ Ω.cm. The PL spectra indicated that CMT2 crystal possesses higher crystalline quality as compared to CMT1 crystal, with lower impurity concentration and defects. The fabrication CdMnTe single element planar detectors under the 59.5 keV 241^Am radiation showed that the energy resolution of CMT1 and CMT2 crystals was 17.2% and 12.7%, respectively. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)