A novel microelectronic gas sensor utilizing carbon nanotubes for hydrogen gas detection

A novel microelectronic gas sensor utilizing carbon nanotubes (CNTs) in a thin-layered Pd/CNTs/n(+)-Si structure for hydrogen detection has been achieved. The sensor is fabricated on an n-type silicon wafer, which is needed as an ohmic supporting substrate. Multiwalled CNTs were grown selectively on the substrate via catalytic activation with microwave plasma enhanced chemical vapor deposition. The I-V characteristics of the sensor exhibit Schottky diode behavior at room temperature with marked sensitivity or current changes in the presence of hydrogen. Increasing detection sensitivity in hydrogen sensing was observed with increasing operating temperature. The results demonstrate that CNTs configured as a gas sensor has high sensitivity to hydrogen over a wide temperature range. Behaviors of the sensor in the presence of hydrogen and at elevated temperature were discussed. The successful utilization of CNTs in gas sensors may open a new door for the development of novel nanostructure gas-sensing devices. (C) 2003 Elsevier Science B.V. All rights reserved.