High-Performance Air-Stable n‑Type Carbon Nanotube Transistors with Erbium Contacts

• Published in: ACS nano Vol. 7; no. 9; pp. 8303 - 8308
• Main Authors: Shahrjerdi, Davood, Franklin, Aaron D, Oida, Satoshi, Ott, John A, Tulevski, George S, Haensch, Wilfried
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 24.09.2013
• Subjects: Carbon nanotubes; Deposition; Devices; Erbium; Evaporation; Semiconductor devices; Tasks; Transistors; Work functions; carbon nanotube; low work function metals; device yield; n-type transistors
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/nn403935v

So far, realization of reproducible n-type carbon nanotube (CNT) transistors suitable for integrated digital applications has been a difficult task. In this work, hundreds of n-type CNT transistors from three different low work function metalserbium, lanthanum, and yttriumare studied and benchmarked against p-type devices with palladium contacts. The crucial role of metal type and deposition conditions is elucidated with respect to overall yield and performance of the n-type devices. It is found that high oxidation rates and sensitivity to deposition conditions are the major causes for the lower yield and large variation in performance of n-type CNT devices with low work function metal contacts. Considerable improvement in device yield is attained using erbium contacts evaporated at high deposition rates. Furthermore, the air-stability of our n-type transistors is studied in light of the extreme sensitivity of these metals to oxidation.