Applications of II–VI semimagnetic semiconductors

Abstract

Selected possible applications of (Cd, Mn)Te, a classical wide-bandgap semimagnetic semiconductor, will be described. Both the semimagnetic character and the other physical properties of this material give rise to its wide applications. As a semimagnetic semiconductor (Cd, Mn)Te demonstrates “giant Faraday rotation” (of the direction of polarization in a strong static magnetic field) for photons with energy a little below that of the free exciton energy. This effect, which is strongest at low temperatures, is also significant at room temperature. (Cd, Mn)Te-based “Faraday rotators” can be used in optical telecommunications as “optical isolators” between the source of radiation (a strong laser) and the rest of the optical transmission line to avoid having parasitic light reflected back to the laser and disturbing its operation. In (Cd, Mn)Te crystals the Faraday effect is extremely fast. The results of the experiments, showing that the response time of the (Cd, Mn)Te crystals to a pulsed magnetic field is in the range 300–500 fs, will be presented, as well as the possible applications of this super-fast Faraday effect. As a wide-bandgap semiconductor with high stopping power for X- and γ-rays, (Cd, Mn)Te can be applied to the construction of radiation detectors. The required parameters: high resistivity (∼10 10 Ω cm) and a high mobility–lifetime product ( μτ = 3 × 10 −3 cm 2/V) have already been achieved and the results will be described.