EELS and HREM study of tunnelling junctions with A1N and A1ON barriers

摘要

The microstructure and chemical composition of spin tunnel junctions with AlON and AlN barriers have been investigated using high-resolution electron microscopy (HREM) and electron energy loss spectroscopy (EELS). HREM observation shows that plasma-nitrided Al results in thinner tunnel barriers than those obtained with oxygen or oxygen+nitrogen plasma, for the same plasma exposure time. The tunnelling magnetoresistance (TMR) data indicate that the performance of spin tunnel junctions with over-nitridation is better than that with under-nitridation. EELS composition mapping experiments give layer thicknesses consistent with the HREM results and have confirmed the presence of nitrogen in the barrier layer.