Growth and properties of ferromagnet-semiconductor heterostructures for spin injection at room temperature

Summary form only given. We show that spin injection from Fe into GaAs and from MnAs into GaAs is possible, even at room temperature, if the ferromagnetic metal is used as tunneling spin injector, i.e. as a Schottky contact. We utilize the optical signal from a (Ga,In)As LED to probe the spin transport into the semiconductor region. In the first part we discuss in detail the growth of Fe-on-GaAs in an As-free metal MBE chamber, connected directly to the III-V MBE chamber via a UHV interlock. We present the structural and magnetic properties of the Fe/GaAs heterostructures grown under different conditions, and we discuss our results on tunneling-assisted spin injection from ferromagnetic Fe into GaAs at room temperature. In the second part we discuss growth and properties of hexagonal binary MnAs films on GaAs[001], which exhibit a unique atomic interface arrangement due to the large anisotropic lattice mismatch. In the final part we present some very recent results on the MBE grown diluted "ferromagnetic" III-V semiconductors Ga/sub x/Mn/sub 1-x/As and Ga/sub x/Mn/sub 1-x/N.