Design and Fabrication of a Fast Responsive and Highly Sensitive Gas Sensor based on Schottky Hetero-junction of Carbon Nanotubes

In this research, a fast responsive and highly sensitive hetero structure gas sensor is proposed. To fabricate Au/CNT/Ti heterojunction Schottky structure, vertically aligned carbon nanotubes (VACNTs) were deposited on silicon oxide substrate between two metal electrodes using plasma-enhanced chemical vapor deposition method. To study the surface characteristics of the structure, Scanning Electron Microscopy analysis was performed to show the density and well-aligned growth of CNTs. The Titanium and gold metals were used as the electrodes to form schottky and ohmic contacts, respectively. The fabricated sample was exposed to 500, 1000 and 1500 ppm concentrations of N2 and NO2 gases. The response and recovery times of 85 and 154 sec for NO2 and 97 and 190 sec for N2 were measured, respectively. On this basis compare to similar structures, the response and recovery times of the fabricated sensor are shorter. It is observed that the sensitivity of 13.5% and 33.5% occurs for 1500 ppm of NO2 and N2, respectively, which in comparison with the sensistivity to CO and H2S gases, proves that the fabricated structure is suitable for Nitrogen detection applications.