Selective H atom sensors using ultrathin Ag Si Schottky diodes

Schottky diodes with ultrathin silver films on n-Si(111) are used for selective detection of atomic hydrogen. The exothermic adsorption of H atoms on the Ag surface creates hot electrons which may travel ballistically through the metal film and traverse the Schottky barrier. The chemically induced current is measurable (approximate to 0.001 electrons/H atom) as a chemicurrent. After saturation of the adsorption sites, this chemicurrent achieves a steady-state value due to a balance of removal of adsorbed hydrogen and readsorption. The detection limit of the sensors is approximately 10(10) H atoms cm(-2) s(-1). The detectors are completely insensitive to H-2 molecules. (C) 1999 American Institute of Physics. [S0003-6951(99)00526-4].