  This study explores the suitability of semi-insulating compounds,
specifically (Cd,Mn)Te and (Cd,Mn)(Te,Se), as materials for room temperature
X-ray and gamma-ray detectors. These compounds were grown using the Bridgman
method, known for its efficient growth rate. The investigation aims to compare
their crystal structure, mechanical properties, optical characteristics, and
radiation detection capabilities. The addition of selenium to (Cd,Mn)Te
increased the compound's hardness. However, (Cd,Mn)(Te,Se) exhibited one order
of magnitude higher etch pit density compared to (Cd,Mn)Te. Photoluminescence
analysis at low temperatures revealed the presence of defect states in both
materials, characterized by shallow and deep donor-acceptor pair transitions
(DAP). Annealing in cadmium vapors effectively eliminated DAP luminescence in
(Cd,Mn)Te but not in (Cd,Mn)(Te,Se). Spectroscopic performance assessments
indicated that the (Cd,Mn)Te detector outperformed the (Cd,Mn)(Te,Se) detector
in responding to a Co-57 source. The reduced performance in the latter case may
be attributed to either the presence of a deep trap related to deep DAP
luminescence, minimally affected by annealing, or the dominant presence of
block-like structures in the samples, as indicated by X-ray diffraction
measurements. The block-like structures in (Cd,Mn)(Te,Se) showed ten times
larger misorientation angles compared to the (Cd,Mn)Te crystals. (Cd,Mn)Te
crystal revealed excellent single crystal properties, demonstrated by narrower
omega scan widths. The study also highlights the influence of grain boundaries
and twins on crystal structure quality. In our opinion, Bridgman-grown
(Cd,Mn)Te shows greater promise as a material for X-ray and gamma-ray detectors
compared to (Cd,Mn)(Te,Se).
