Epitaxial Metallic Compounds for Ideal Contacts to Compound Semiconductors

摘要

Techniques for forming ideal contacts to compound semiconductors were developed. Atomic level structural characterization techniques, including scanning tunneling and transmission electron microscopy, as well as electrical characterization techniques were used to study the contact formation. By sequential depositions and reactions, metallic layers were first reacted with gallium arsenide to form a metal-gallium-arsenic compound. The consumption of gallium arsenide was controlled by the thickness of the metallic layer deposited. Sequential deposition of gallium or arsenic was used to drive the decomposition of the metal-gallium-arsenic compound, resulting in the solid phase regrowth of gallium arsenide beneath the metallic compound layer. The amount of regrown gallium arsenide could be controlled to atomic length scales by the supply of gallium or arsenic. Magnetization controlled resonant tunneling through buried semi-metallic quantum wells was demonstrated. Further aluminum arsenide was used to terminate gallium arsenide so that atomically abrupt iron aluminum could be grown. Iron aluminum compounds were found to have different growth modes, which correlated with the surface reconstruction. The properties of the films were measured. Finally, GaN films were grown on sapphire and then hafnium and hafnium nitride epitaxial films were grown. Hafnium growth on gallium nitride proceeded via a hafnium nitride interlayer.