Ohmic Contacts to Phase Change Materials for RF Switches
Abstract
Researchers at The Pennsylvania State University investigated ohmic contacts to the phase change material germanium telluride and gained a fundamental understanding of ohmic contacts for radio frequency switches fabricated from germanium telluride. Using x-ray photoelectron spectroscopy, they examined pre-metallization surface preparations of germanium telluride, and they studied how the resulting germanium-to-tellurium ratio and effectiveness of removal of the native oxide affected contact resistance. They also surveyed reactivity of germanium telluride with metals across the periodic table using transmission electron microscopy of thin-film samples and thermodynamic calculations. An unexpected trend in contact resistance with the work function of the first metal layer in the metallization stack was explained by understanding the effect of interfacial reactions with germanium telluride. Molybdenum as the first layer in an ohmic contact stack resulted in contact resistances near 0.004 Ohm-mm (5 X 10 (exp -9) Ohm-cm2 ) when an in situ Ar+ ion pre-metallization surface treatment was used. A tin-based contact also provided very low contact resistance, permitting an ex situ surface treatment but requiring annealing. Its low resistance was ascribed in part to the formation of tin telluride.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 20, 2020
- Accession Number
- AD1091263
Entities
People
- Suzanne E Mohney
Organizations
- Pennsylvania State University