Low-Resistance, High-Yield Electrical Contacts to Atom Scale Si:P Devices Using Palladium Silicide

• Published in: Physical review applied 2019-03, Vol.11 (3), Article 034071
• Main Authors: Schmucker, Scott W., Namboodiri, Pradeep N., Kashid, Ranjit, Wang, Xiqiao, Hu, Binhui, Wyrick, Jonathan E., Myers, Alline F., Schumacher, Joshua D., Silver, Richard M., Stewart, M. D.
• Format: Article
• Language: English
• Subjects: 2-dimensional systems; Devices; Doped semiconductors; Electrical conductivity; MATERIALS SCIENCE; NANOSCIENCE AND NANOTECHNOLOGY; Nanostructures; Quantum transport; Sample preparation; Scanning tunneling microscopy
• ISSN: 2331-7019; 2331-7019
• DOI: 10.1103/PhysRevApplied.11.034071

Scanning tunneling microscopy (STM) enables the fabrication of two-dimensional δ-doped structures in Si with atomistic precision, with applications from tunnel field-effect transistors to qubits. The combination of a very small contact area and the restrictive thermal budget necessary to maintain the integrity of the δ layer make developing a robust electrical contact method a significant challenge to realizing the potential of atomically precise devices. We demonstrate a method for electrical contact using Pd2Si formed at the temperature of silicon overgrowth (250 °C), minimizing the diffusive impact on the δ layer. Here, we use the transfer length method to show our Pd2Si contacts have very high yield (99.7% +0.2% –1.5%) and low resistivity (272 ± 41 Ω μm) in contacting mesa-etched Si:P δ layers. We also present three terminal measurements of low contact resistance (