The influence of nonmagnetic seed layers on the magnetotransport properties of magnetic tunnel transistors with a silicon collector

Abstract

The magnetotransport properties of magnetic tunnel transistors (MTTs) with a CoFe/Cu/NiFe spin-valve base and a Si(001) collector are studied as a function of seed layer material and thickness. The insertion of a nonmagnetic Cu or Au seed layer between the metal spin valve and the silicon is found to significantly enhance the output current and magnetic-field sensitivity of the MTT device. In contrast, the use of a Pt or Pd seed layer only slightly improves the properties of the MTT, while seed layers of Ta and Ti are found to deteriorate the output current and tunnel barrier breakdown voltage of the MTTs. Secondary-ion-mass spectroscopy is used to provide complementary information about the base/collector interface properties of the MTTs with and without seed layers. © 2005 American Institute of Physics.