ATOMICALLY CONTROLLED GROWTH OF GAAS/NIAL/GAAS STRUCTURES BY MOLECULAR-BEAM EPITAXY

The morphology of molecular-beam epitaxy (MBE) grown GaAs/NiAl/GaAs structures using scanning tunneling microscopy (STM) was investigated. Improving the flatness of the NiAl layer is achieved by improving the wettability of NiAl on GaAs by using a Ni template and increasing the island density by low-temperature growth. This method gives a continuous, flat NiAl film with a mean roughness of one monolayer. A GaAs overlayer with a roughness of two monolayers or less is obtainable by using low-temperature migration enhanced epitaxy (MEE).