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 (≈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 1010 H atoms cm−2 s−1. The detectors are completely insensitive to H2 molecules.