Influence of Si doping on magnetic properties of (Ga,Mn)As

We have systematically investigated the magnetic properties of Si-doped (Ga,Mn)As films. When the Si content is low, both Curie temperature (TC) and carrier density (p) decrease compared with undoped (Ga,Mn)As, whereas a monotonic increase of TC and p is observed with further increase in the doping content of Si. We discuss the possible mechanism for the changes obtained by different Si doping contents and attribute the results to a competition between the existence of SiGa (Si substitutes for Ga site) that acts as a donor and SiI (Si interstitials) which is in favor of the improvement of ferromagnetism.