In this work we present a simple pathway to obtain large single-crystal graphene on copper (Cu) foils with high growth rates using a commercially available cold-wall chemical vapour deposition (CVD) reactor. We show that graphene nucleation density is drastically reduced and crystal growth is accelerated when: (i) using ex situ oxidized foils; (ii) performing annealing in an inert atmosphere prior to growth; (iii) enclosing the foils to lower the precursor impingement flux during growth. Growth rates as high as 14.7 and 17.5 μ m min −1 are obtained on flat and folded foils, respectively. Thus, single-crystal grains with lateral size of about 1 mm can be obtained in just 1 h. The samples are characterized by optical microscopy, scanning electron microscopy, x-ray photoelectron spectroscopy, Raman spectroscopy as well as selected area electron diffraction and low-energy electron diffraction, which confirm the high quality and homogeneity of the films. The development of a process for the quick production of large grain graphene in a commonly used commercial CVD reactor is a significant step towards an increased accessibility to millimetre-sized graphene crystals.
21 February 2008 in The Journal of Physical Chemistry C
We have investigated the possibility of isolating the step-induced in-plane uniaxial magnetic anisotropy in films on which nanoscale surface ripples were fabricated by the ion sculpting technique. For rippled Fe films deposited on flat Ag(001), the steps created along the ripple sidewalls are shown to be the only source of uniaxial anisotropy. Ion sculpting of ultrathin magnetic films allows one to selectively study the step-induced anisotropy and to investigate the correlation between local atomic environment and magnetic properties.
This work reports an electronic and micro-structural study of an appealing system for optoelectronics: tungsten disulphide (WS2) on epitaxial graphene (EG) on SiC(0001).