title: Water-assisted growth of uniform 100 mm diameter SWCNT arrays.
abstract: We report a simple method for growing high-quality single-walled carbon nanotube (SWCNT) arrays on 100 mm wafers via the addition of water vapor to highly purified gases during the CNT growth step. We show that adding a small amount of water during growth helps to create a uniform catalyst distribution and yields high-quality (Raman G/D of 26 ± 3), high-density (up to 6 × 10(11) cm(-2)) and uniform SWCNT arrays on 100 mm large wafers. We rationalize our finding by suggesting that the addition of water decreases catalyst mobility, preventing its coarsening at higher temperatures. We also report a new mechanism of catalyst inactivation in wafer-scale growth using ultrapurified gas sources by the formation of large, 5 ± 3 μm iron particles. We found such formations to be common for substrates with large temperature gradients, such as for wafers processed in a typical cold-wall chemical vapor deposition reactor.
authors.affiliation: Nanoscience for Energy Technology and Sustainability, Department of Mechanical and Process Engineering, ETH Zurich , Sonneggstrasse 3, Zürich CH-8092, Switzerland.
authors.forename: Roman M
authors.initials: RM
authors.lastname: Wyss
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Klare
authors.forename: Hyung Gyu
authors.initials: HG
authors.lastname: Park
authors.forename: Aleksandr
authors.initials: A
authors.lastname: Noy
authors.forename: Olgica
authors.initials: O
authors.lastname: Bakajin
authors.forename: Valentin
authors.initials: V
authors.lastname: Lulevich
keywords: aligned SWCNT array; catalyst inactivation; catalyst mobility; catalyst ripening; wafer scale CNT synthesis; water assisted SWCNT growth