Spin Injection Enhancement through Schottky Barrier Engineering
Abstract
High-efficiency spin injection has been achieved from iron into GaAs through careful doping near the Schottky barrier at the metal-semiconductor interface. However the inevitable highly doped or depleted regions near the interface reduce the spin coherence times of carriers. We describe a new way to control the Schottky barrier to improve spin injection, through the use of short-period superlattices near the interface. The AlSb valence band lies 550 meV below the Fe Fermi energy. The InAs conduction band lies 140 meV above the AlSb valence band, and thus 410 meV below the Fe Fermi energy. It is therefore possible through confinement in the InAs layer to make the effective barrier vanish. For such a structure, the doping in the semiconductor does not need to vary significantly near the interface with the metal, and thus the spin coherence times should be long. We predict a 29.5Å InAs/13.5Å AlSb (001)-grown superlattice will have this property at 300K. Spin lifetimes in (110)-grown superlattices should be even longer, and a (110)-grown 15.5Å InAs/8.5Å AlSb superlattice should have a vanishing effective barrier at 300K. This work was supported by DARPA/ARO.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MARU26006P