Size dependence of the magnetic and electrical properties of the spin-valve transistor

The electrical and magnetic properties of the spin-valve transistor (SVT) are investigated as a function of transistor size. A new fabrication process, designed to study the size dependence of the SVT properties, uses: silicon-on-insulator (SOI) wafers, a combination of ion beam and wet etching and a negative tone photoresist (SU8) as an insulating layer. The Si/Pt emitter and Si/Au collector Schottky barrier height do not depend on the transistor dimensions. The parasitic leakage current of the Si/Au collector is, however, proportional to its area. The relative collector current change with magnetic field is 240%, independent of size, while the transfer ratio starts to decrease for SVTs with an emitter area below 25 /spl times/ 25 /spl mu/m/sup 2/. The maximum input current is found to be limited by the maximum current density allowed in the base (1.7 /spl times/ 10/sup 7/ A/cm/sup 2/), which is in agreement with the maximum current density for spin valves.