Single crystal growth under controlled activity of constituent elements of II-VI ternary solid solution semiconductor with Hg as one of the elements

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MCT(Hg_<1-X>Cd_XTe) is attractive as an infrared detetor in the 10 mum wavelength region. Recently, in addition to the infrared detector, applications have extended to a wide range of the compositions from x=0.70 for a photodetector at 1.3 mum wavelength for optical fober telecommunication, to x=0.90 as a gamma-ray detector. The usefulness of MCT over the entire composition range requires more convenient crystal growth methods which enable us to grow homogeneous single crystals with a target composition. For this purpose, we adopted a modified THM(Travelling Heater Method) to grow a homogeneous single crystals with a target composition. A CdTe single crystal was used as a feed and Hg reservoir chamber was used to control the Hg activity in Te solvent. From the growth experiments, it was confirmed that lowering speed of the growth tube had to be less than 3 mm/day and homogeneous single crystals were to be grown. Compositions with x higher than x=0.60 can be grown by increasing P_<Hg> or decreasing T_g. PL (photoluminescence spectra) was measured at 4.2 K and composition dependence of the band gap was clarified.