DEVELOPMENT OF THE SPIN-VALVE TRANSISTOR

As the easiest experimental approach, GMR (Giant Magnetoresistance) is usually measured using the Current in Plane (CIP)-GMR. The spin-valve transistor has previously been presented as a spectroscopic tool to m easure Current Perpendicular to the Planes (CPP)-GMR. Hot electrons cr oss the magnetic multilayer base quasi-ballistically and the number re aching the collector depends exponentially on the perpendicular hot el ectron mean free path. Collector current changes of 390% at 77K have a lready been measured. Apart from the substantial fundamental value, su ch properties may be useful for sensor applications. The electron ener gy range fills the gap between the Fermi surface transport in resistan ce measurements and other hot electron techniques such as spin polaris ed electron energy loss spectroscopy (SPEELS). The preparation problem of the spin-valve transistor and metal base transistor structures in general, the deposition of a device quality semiconductor on top of a metal, has now been tackled by bonding of two semiconductor substrates during vacuum deposition of a metal: an excellent bond is achieved at room temperature. TEM photos show a continuous buried metal film. Apa rt from preparation of various metal base transistor like structures, many other fields may benefit from this new technique.