Optical properties and functions of dilute magnetic semiconductors

The magneto-optical effect in dilute magnetic semiconductors (DMSs) is directly related to the interaction between the d electrons of the transition metal ions and the s, p electrons of the host semiconductor. We show the advantages of the magneto-optical effect of DMSs as regards fabricating magneto-optical waveguide devices that can be integrated with other semiconductor optical devices. We also discuss the advantages of magneto-optical spectroscopy for characterizing DMSs. Intrinsic ferromagnetism of In1-xMnxAs, Ga1-xMnxAs and Zn1-xCrxTe is confirmed by using magnetic circular dichroism (MCD) spectroscopy. The MCD analyses also show that Zn1-xTMxO (TM = Mn, Fe, Co, Ni or Cu), Ga1-xMnxN and Ga1-xCrxAs are paramagnetic DMSs with the s, p-d exchange interaction. Ferromagnetic behaviours observed in some transition metal doped ZnO, GaN and GaAs samples are attributed to unidentified precipitations not detectable by means of x-ray diffraction analysis.