Dresden 2006 – scientific programme

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HL: Halbleiterphysik

HL 9: Poster I

HL 9.86: Poster

Monday, March 27, 2006, 15:15–17:45, P3

Spin Injection into Nonmagnetic Semiconductors: Application of a Unified Transport Theory — •U. Wille and R. Lipperheide — Abteilung Theoretische Physik, Hahn-Meitner-Institut Berlin, Glienicker Str. 100, D-14109 Berlin, Germany

In a recent paper [PRB 72, 165322 (2005)], we have developed a theory unifying ballistic and diffusive spin-polarized electron transport in ferromagnet/semiconductor heterostructures. It is based on our previously formulated “thermoballistic” description of (spinless) electron transport in parallel-plane semiconductor structures [PRB 68, 115315 (2003)].

In the present contribution, we apply the unified transport theory in the study of the injection of spin-polarized electrons into nonmagnetic semiconductors, emphasizing the transition from the purely diffusive to the purely ballistic transport regime. We consider various examples: (i) For heterostructures involving ferromagnetic contacts and a homogeneous semiconducting sample without space charge, we study spin injection driven by an external electric field over a broad range of system and material parameters. (ii) The effect of a Schottky barrier piling up at the interface between a metallic ferromagnet and a semiconductor is analyzed. (iii) Within an extended formulation of the unified theory, we consider spin injection out of a (nondegenerate) dilute magnetic semiconductor.

Our results are discussed in comparison with previously obtained theoretical results.