Magnetotransport properties and the annealing effect of (Ga,Mn)As/Si heterostructures and substrate-free (Ga,Mn)As films

We investigated the properties and annealing effects of substrate-free (Ga,Mn)As films prepared by etching Si substrates from (Ga,Mn)As/Si structures, and compared the results with those from (Ga,Mn)As/Si heterostructures. The substrate-free (Ga,Mn)As films with 6% Mn content were annealed at 250 °C as a function of time. From Hall-effect measurements, the Curie temperature of substrate-free (Ga,Mn)As films was estimated to be 87 K for an as-grown film, enhanced up to 152 K after low-temperature annealing for 60 min. We found that the (Ga,Mn)As films grown on Si substrates show a relatively high Curie temperature.