Ultrasensitive Gas Sensors Based on Vertical Graphene Nanowalls/SiC/Si Heterostructure

Gas sensors, which play an important role in the safety of human life, cover a wide range of applications including intelligent systems and detection of harmful and toxic gases. It is known that graphene is an ideal and attractive candidate for gas sensing due to its high surface area and excellent mechanical, electrical, optical, and thermal properties. However, in order to fully realize its potential as a commercial gas sensor, demand for a graphene-based device of low-limit detection, high sensitivity, and fast response time needs to be met. Here, we demonstrate a metal/insulator/semiconductor (MIS) based gas sensor consisting of as-grown epitaxial graphene nanowalls (EGNWs)/silicon carbide (SiC)/silicon (Si) structure. The unique edge dominant three-dimensional (3D) EGNWs based MIS device achieved an extraordinarily low limit of detection (0.5 ppm) and unprecedented sensitivity (82 μA/ppm/cm