Centimeter-Scale Ge-Assisted Grown Graphene Directly on SiO2/Si for NO2 Gas Sensors.

For the manufacture of graphene based electronic devices, graphene growth directly on SiO2/Si substrates is a prerequisite. However, the problem of metal contamination is a key issue that cannot be avoided when synthesizing graphene on SiO2/Si substrates. Additionally, the direct fabrication of patterned graphene still suffers from inefficient and low repeatable problems. In this article, an approach based on a germanium (Ge)-assisted chemical vapor deposition (CVD) is proposed. It can produce graphene directly on any dielectric substrates. Graphene is grown directly on Ge-covered SiO2/Si substrates due to the catalysis of Ge. By depositing the second Ge layer with a pattern by a designed hard mask onto the as-grown centimeter-scale and continuous graphene on SiO2/Si substrates followed by etching the graphene and removing the Ge, the monolayer graphene pattern was acquired. This process has the advantages of no metal pollution and high repeatability. Subsequently, the patterned and highly conductive graphene prepared on SiO2/Si substrates was used for gas sensor. The gas sensor exhibited well NO2 gas sensing properties because of large charge transferred from graphene to NO2 molecules. [ABSTRACT FROM AUTHOR]