Room-temperature high-sensitivity detection of ammonia gas using the capacitance of carbon/silicon heterojunctions

Ammonia (NH(3)) sensors based on carbon/silicon (C/Si) heterojunctions are demonstrated at room temperature (RT). Upon exposure to NH(3) molecules (0.2 ml l(-1)) at RT, the interface capacitance of C/Si junction increases dramatically, to about 230%. The results show that C/Si junctions have high NH(3) gas sensitivity, rapid response and high recovery speed at RT. This phenomenon can be attributed to the change of the potential barrier width of the junction, which is caused by the adsorption of NH(3) gas molecules. The C/Si junctions can greatly amplify the detection sensitivity of the nano-sized carbon so that the C/Si junctions act as excellent RT gas sensors.