Ferromagnetic metal/semiconductor heterostructures for magneto-electronic devices

We have successfully grown single crystal Fe films on InAs(100) and InAs(gr aded)/GaAs(100) substrates using molecular beam epitaxy. In situ magneto-op tical Kerr effect (MOKE) and ex situ alternating gradient field magnetometr y (AGEM) measurements show that the films have well defined magnetic proper ties, and I-V measurements in the temperature range 2.5-304 K shaw that Fe forms an ohmic contact on InAs. This demonstrates that Fe/InAs is a very pr omising system for use in future magneto-electronic devices as it has bath favorable magnetic and electrical properties. We also show that with carefu l substrate preparation and suitable growth conditions Fe/GaAs films do not exhibit a magnetically 'dead' layer at the interface. A spin-polarized fie ld effect transistor based on Fe/InAs/GaAs has been proposed, which could o perate using either an external electric field or an external magnetic fiel d. (C) 2000 Elsevier Science S.A. All rights reserved.