ABSTRACT
The ferromagnet/semiconductor (FM/SC) hybrid structure is one of the key issues to realize spin-related devices, such as the spin-controlled field effect transistor (Spin-FET) [1]. For the Spin-FET and other types of spin devices, spin-polarized electron injection into semiconductor is one of the most important research subjects. However, to date, efficient spin injection with the FM/SC hybrid structure remains a challenging task, although it is one of the promising candidates for spin-related devices, that can be operated at room temperature. The only successful result was obtained in the case of diluted magnetic semiconductor (DMS)[2][3j. Moreover, several theoretical reports suggest that high efficiency spin injection is impossible in the FM/SC hybrid system due to conductivity mismatch between ferromagnet and semiconductor [4] [5]. Recently, high efficiency spin injection with Fe/GaAs was demonstrated by using Schottky tunneling barrier [6 ] [7]. The Fe/InAs hybrid structure has attracted considerable attention, because it is expected to form an ohmic contact, in which more efficient electron injection is expected than in a Schottky contact system such as the Fe/GaAs. In addition, there is an advantage for spin-related devices, due to the larger spinorbit coupling in InAs 2DEG channel than in GaAs [8 ] [9]. In this paper, we show that spinpolarized electrons can be injected directly from an Fe thin film into InAs.
