  V-telluride superlattice thin films have shown promising performance for
on-chip cooling devices. Recent experimental studies have indicated that device
performance is limited by the metal/semiconductor electrical contacts. One
challenge in realizing a low resistivity contacts is the absence of fundamental
knowledge of the physical and chemical properties of interfaces between metal
and V-telluride materials. Here we present a combination of experimental and
theoretical efforts to understand, design and harness low resistivity contacts
to V-tellurides. Ab initio calculations are used to explore the effects of
interfacial structure and chemical compositions on the electrical contacts, and
an ab initio based macroscopic model is employed to predict the fundamental
limit of contact resistivity as a function of both carrier concentration and
temperature. Under the guidance of theoretical studies, we develop an
experimental approach to fabricate low resistivity metal contacts to
V-telluride thin film superlattices, achieving a 100-fold reduction compared to
previous work. Interfacial characterization and analysis using both scanning
transmission electron microscopy and energy-dispersive x-ray spectroscopy show
the unusual interfacial morphology and the potential for further improvement in
contact resistivity. Finally, we harness the improved contacts to realize an
improved high-performance thermoelectric cooling module.

Materials Science