The spin-valve transistor

The spin-valve transistor is a magnetoelectronic device that can be used as a magnetic field sensor. It has a ferromagnet-semiconductor hybrid structu re. Using a vacuum metal bonding technique, the spin-valve transistor struc ture Si/Pt/NiFe/Au/Co/Au/Si is obtained. It employs hot electron transport across the spin valve (NiFe/Au/Co). The hot electrons are injected into the spin valve across the Si/Pt Schottky diode. After traversing across the sp in valve these hot electrons are collected across the Au-Si Schottky diode with energy and momentum selection. The output current is found to be extre mely sensitive to the spin-dependent scattering of hot electrons in the spi n valve. This gives a magnetocurrent above 200% in a few oersted of magneti c field at room temperature. The different physical effects which govern th e output current of the device are examined by studying different types of spin-valve transistors that have Si/Au, Si/Pt and Si/Co collector Schottky diodes and Si(100) and Si(111) orientations. It has been observed that alon g with the Schottky diodes the vacuum metal bonding also plays an important role in determining the output current. In addition, it is realized that c ollector diodes with extremely low leakage currents, are essential in order to observe huge magnetotransport properties at room temperature.