| AVS 54th International Symposium | |
| Magnetic Interfaces and Nanostructures | Thursday Sessions |
| Session MI-ThM |
| Session: | Magnetic Semiconductors I |
| Presenter: | I.N. Gatuna, University of Washington |
| Authors: | I.N. Gatuna, University of Washington F.S. Ohuchi, University of Washington M.A. Olmstead, University of Washington |
| Correspondent: | Click to Email |
The quest to functionalize semiconductors with additional magnetic properties through synthesis of dilute magnetic semiconductors (DMS) has led to a deeperunderstanding of semiconductor physics and the development of new magneticmechanisms. However, most current DMS materials (e.g., Mn-doped GaAs) are magnetic only well below room temperature, and/or have only limited compatibility with existing silicon electronics. We have investigated transition metal (TM) doping of the intrinsic vacancy semiconductor Ga2Se3 to address both scientific and technical goals. The intrinsic vacancies of this III-VI, zinc-blende-based semiconductor open possibilities for self-compensation as well as supply highly anistropic and polarizable band edge states. Ga2Se3 is also closely lattice matched to Si and may be grown heteroepitaxially on Si with high quality interfaces. Our first principles computations of X:Ga2Se3 (X = Mn, V, Cr, concentrations 5% to 16%) reveal that X atoms hybridize with neighboring Se in the p-d hybridization typical of III-V and II-VI DMS materials. This hybridization spin-polarizes states near the Fermi level in these T =0 calculations, and lowers the energy of the Se lone-pair orbitals that neighbor vacancies, reducing their prominent role in determining the properties of intrinsic Ga2Se3. There are distinct differences between substitution on a vacancy or for a Ga. Anisotropic, hole-like conductivity is predicted when X is located in a Ga site, while for X situated in a vacancy, a half-metallic state with an isotropic conductivity appears likely. Our calculations suggest that Mn offers the best choice for the dopant, perhaps because its 3d5 electronic configuration offers a large (~ 0.5 eV) separation of spin up and spin down states near the Fermi level, reducing the metallic densities of states at the Fermi level for all doping concentrations. The large energy splitting suggests that doped Ga2Se3 may be a suitable material for spintronics applications athigher temperatures than these T = 0 initial calculations.
This work was supported by NSF grant DMR 0605601, the Japan Science Promotion International Program, NIMS (Japan) - UW Joint Research Pact and NIMS (Japan) Internal Research Fund.