A novel "etching-precipitation" method is proposed and developed for the direct synthesis of graphene on dielectric substrates. In this method, graphene precipitates from the Fe-C solid solution film during selective etching of Fe using Cl 2 gas. Few-and multi-layer graphene is fabricated directly on quartz glass and SiO 2 /Si substrates without Fe residue at a growth temperature of 500-650 °C, which is a significantly lower temperature than used in the conventional chemical vapor deposition method. The 6-to 7-layer graphene synthesized at 650 °C shows a volume resistivity of 80-140 μΩ cm. The average number of layers can be easily controlled in a linear fashion with the initial carbon feed, which is proportional to the thickness of the starting Fe-C films. Line-patterned multi-layer graphene is also fabricated by simply pre-patterning the starting Fe-C film although its structure is somewhat different from typical graphene ribbons. "Etching-precipitation" will be a practical route to synthesize graphene with micro-patterns directly onto device substrates of arbitrary sizes.

Cathodoluminescence (CL) spectra were measured from polycrystalline Ga–In–O (GIO) films prepared by the molecular precursor method (MPM). Bandgap-energy (E g) and conductivity were successfully controlled by changing in the mixing ratio of the Ga and In precursor solutions. Although none of the films exhibited a near-band-edge emission, their CL emissions exhibited energy shifts by reflecting changes in E g and ligand field in the GIO alloys. The results indicate a practical use of MPM-grown GIO films for deep ultraviolet optoelectronic devices.