Cyclotron resonance of localized electrons inn-type Cd-Mn-Se

Electron cyclotron resonance has been observed in a wide-gap semiconductor ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Se at helium temperatures where practically all electrons are bound on donors. The number of electrons participating in the cyclotron resonance absorption of far-infrared radiation increases rapidly as the resonance magnetic field is raised from 1.5 to 5 T. The origin of the implied extended electronic states is attributed to an Anderson-type transition in clusters of donors of higher than average concentration and volume which is greater than (4π/3) (magnetic length${)}^3$, resulting from random fluctuations of local donor density.