Metal-insulator transition in the persistent photoconductor Cd_1-xMn_xTe: In

Persistent photoconductivity has been used to probe the metal-insulator transition in the diluted magnetic semiconductor Cd_1-xMn_nTe : In. We have measured the d.c. conductivity of Cd_0.92Mn_0.08Te : In with tunable photogenerated carrier concentration, from the insulating phase up to ∼ 1.2n_c in the same sample. In the insulating phase, Efros-Shklovskii variable range hopping conduction is observed. In the metallic phase the temperature dependence of the conductivity is adequately described by quantum corrections to the zero-temperature conductivity due to the effects of electron-electron interaction and weak localization. In the critical region the scaling theory of electron localization has been applied. We observe a critical carrier concentration ∼ 2.3 × 10¹⁷ cm^-3, and a critical conductivity exponent close to one.