High-efficiency thin-film superlattice thermoelectric cooler modules enabled by low resistivity contacts
He, Y., Leonard, F., Medlin, D. L., Baldasaro, N., Temple, D. S., Barletta, P., & Spataru, C. D. (2018). High-efficiency thin-film superlattice thermoelectric cooler modules enabled by low resistivity contacts. Advanced Electronic Materials, 4(3), . DOI: 10.1002/aelm.201700381
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 contact is the absence of fundamental knowledge of the physical and chemical properties of interfaces between metal and V-telluride materials. This study presents 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, an experimental approach is developed 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 unusual interfacial morphology and the potential for further improvement in contact resistivity. Finally, the improved contacts are harnessed to realize an improved high-performance thermoelectric cooling module.