Structural characterization of base/collector interfaces for magnetic tunnel transistors grown on Si(001)

摘要

The microstructure and composition of magnetic tunnel transistors (MTTs), grown on Si(001) collector substrates, have been investigated using high-resolution and analytical electron microscopy. The effects of different seed layers, including a ferromagnetic metal Fe, and noble metals Pd, Ir, Re, and Ru, on the tunnel junction morphology were studied. The Pd seed layers reacted with the Si substrate, and gave MTTs with a small transfer ratio and relatively large leakage current. Devices based on Ir and Re seed layers invariably shorted out, as did most of those with Ru seed layers. Very thin Fe seed layers gave flat and more abrupt seed-layer/Si substrate interfaces, and among the samples studied, the best transport properties were achieved for a thin Fe seed layer in combination with Co_(70)Fe_(30) base layer.