In situ control of dewetting of Cu thin films in graphene chemical vapor deposition

Abstract

Abstract.Chemical Vapor Deposition (CVD) on Cu thin films is a promising approach for the large area formation of graphene on dielectric substrates, but a fine control of the deposition parameters is required to avoid dewetting of the Cu catalyst. In this paper we report on the study of the Cu dewetting phenomena by monitoring the intensity of the infra-red emission from the film surface during Rapid Thermal CVD of graphene. The reduction of Cu film coverage consequent to dewetting is detected as a variation of sample's emissivity. Results indicate three time constants of dewetting, describing three typical stages, hole formation, propagation and ligament breakup. Slowing the first incubation stage by tuning pressure in the chamber allows for an effective surface activation resulting in the deposition of graphene at temperatures lower than in the case of Cu foils.

High Temperature Growth of Graphene from Cobalt Volume: Effect on Structural Properties

“…Another important difference is that we observe suspended graphene on the metal discontinuities in the RTP samples, and not in the ones processed in the quartz tube. The situation is similar to that reported for Cu films [ 20 , 23 ], despite the melting T of Co is about 400 °C higher than Cu.…”

“…The coverage of the Co film in samples deposited by means of RTP overcomes 95%, whereas it is less than 90% in the case of deposition in the conventional quartz furnace. This suggests that the duration of the heating step plays a role [ 23 ], since in the first case temperature is raised at a rate of 5 °C/s, due to instrumental limitations, and with a rate 10 times lower in the second. Another important difference is that we observe suspended graphene on the metal discontinuities in the RTP samples, and not in the ones processed in the quartz tube.…”

“…The scenario then considers two competing mechanisms taking place in RTP during the isothermal exposure to the precursor, graphene growth and film dewetting. Carbon precipitation on the metal surface obstacles dewetting [ 23 ], which is on the contrary favored by Co-C alloying at the high temperature (T = 1000 °C) involved.…”

RETRACTED: Synthesis of carbon nanotubes using the cobalt nanocatalyst by thermal chemical vapor deposition technique

“…While weak contact between the catalyst and substrate favors a tip-growth mechanism, a strong interaction promotes base-growth [12][13]. The growth of CNTs can be divided into four steps: (1) supply of carbon source on the catalyst surface by adsorption and the subsequent catalytic decomposition of the adsorbed carbon by carbon atoms; (2) desorption of the carbon atoms into a gas phase; (3) diffusion of the carbon atoms away from the catalyst surface through bulk or surface diffusion; and (4) precipitation and formation of a graphite structure [14][15][16]. Formerly, some synthesis methods of carbon nanotubes, related materials and metal atoms agglomerate are analyzed [17][18][19][20][21][22][23][24][25].…”

Raman analysis of strained graphene grown on dewetted cobalt

“…Graphene was synthesized via rapid cooling CVD, as proposed in Amato et al, [10] using a rapid thermal annealing apparatus. [19] The substrate and catalyst of choice was Co polycrystalline thin film, 500 nm thick, deposited by radio frequency sputtering onto Si substrates with 500-nm thermal SiO 2 . Prior to the graphene deposition, the Co/SiO 2 substrate was cleaned in sonic bath with acetone and ethanol.…”