D−Levels inCd1−xMnxSe

The observation of cyclotron resonance in ${\mathrm{Cd}}_{0.9}$ ${\mathrm{Mn}}_{0.1}$Se implies the presence of free carriers at densities of 1.0×${10}^{14}$/${\mathrm{cm}}^3$. Transport and far-infrared data are shown to be consistent with a model in which there are $D^{-}$ levels in the sample under thermal-equilibrium conditions. It is argued that the $D^{-}$ levels result from fluctuations in the conduction-band edge due to random Mn concentration fluctuations. An activated dc conductivity also supports the model.