Magnetotransport in ferromagnetic pn-diode of (Ga,Mn)As and (Ga,Mn)N

摘要

The (Ga,Mn)As and (Ga,Mn)N pn-diodes were fabricated by using Molecular Beam Epitaxy (MBE). The structure of the tunnelling GaAs diodes is shown in Fig.1. Firstly, heavily doped n+-GaAs was grown on top of n-type (10^18cm{sup}(-3)) GaAs substrate. After that the magnetic Mn doped GaAs layer with different Mn concentrations was grown by MBE. The mole fraction of Mn was varied between 2% and 5%. As Mn act as an acceptor, the top layer is p-type. The growth temperature was only 230°C in order to inhibit formation of secondary phases and segregation of Mn at the surface. Finally, the ohmic contacts were evaporated by an electro-beam evaporator. The structure of the (Ga,Mn)N pn-diode was similar, except the fact that the n- and p-type areas were in the opposite order. In addition, the n-type magnetic layer (Ga,Mn)N was made by solid state diffusion of Mn inside the MBE chamber.