Gamma-Ray Response of Semi-Insulating CdMnTe Crystals

Semi-insulating Cd
_0.9
Mn
_0.1
Te:In crystals are grown by vertical Bridgman method. The segregation coefficient of Mn in CdTe is nearly 1 so that all the CdMnTe samples obtained from one ingot have nearly a same Mn composition. Also sulfur-based passivation effectively prevent the formation of Te-oxide but large amount of Mn exist as a MnO on the CdMnTe surface. The resistivity of CdMnTe samples are low 10
¹⁰
Omegacm and well resolved
²⁴¹
Am gamma peaks are seen for all detectors. The difference in spectral response can be attributed to the effect of excess Te and conductivity change due to over-compensation induced by indium segregation in CdMnTe. The mobility-lifetime products evaluated from the dependence of peak location on the bias voltage are 1 times 10
^-3
cm
²
/V. The higher mobility-lifetime products in our CdMnTe crystals than other previous reports are assumed due to minimization of impurity contents in MnTe by several zone refining process.