Effect of an atomically matched interface structure on Fermi-level pinning at metal/p-Ge interfaces

Using low-temperature molecular beam epitaxy (LTMBE), we demonstrate high-quality heterointerfaces consisting of CoFe alloys and germanium (Ge) with a good atomic matching at the (111) plane. Electrical properties of the atomically matched CoFe/p-Ge(111) junctions with the area of (S) < similar to 10 mu m(2) clearly show the suppression of the Fermi-level pinning (FLP) effect, similar to the features of the atomically matched Fe3Si/p-Ge(111) junctions with S < similar to 10 mu m(2) in our previous work. This means that the suppression of FLP is independent on a kind of metals. As a result, we conclude that the formation of the atomically matched metal/Ge interfaces with almost no defects is important to suppress FLP.