Growth and Properties of (Al, Ga)As / NiAl / (Al, Ga)As: An Epitaxical Semiconductor / Metal / Semiconductor System

The epitaxical and thermally stable NiAI/(AI, Ga)As system is shown to meet all of the basic materials criteria for buried metal/compound semiconductor heterostructures. We describe the growth of these heterostructures by molecular beam epitaxy. Even the thinnest buried NiAI films grown thus far (1.5 nm) are electrically continuous and metallic. Electron tunneling and lateral transport measurements provide strong evidence for size quantization in NiAl films thinner than 3.5 nm. The merging of compound semiconductor tunneling barriers with epitaxical metallic quantum wells and the ability to selectively contact buried metallic quantum wells is expected to yield novel three-terminal devices.