The Impact of $\hbox{TiO}_{2}$ Interface Layer on a Pd/n-LTPS Schottky Diode Hydrogen Detecting Performances

The hydrogen detecting performances of Pd/n-LTPS Schottky diodes, with and without a TiO
₂
interface layer fabricated on glass substrates, were studied in detail. The n-LTPS film, an n-type low-temperature prepared polysilicon film, is formed by annealing an amorphous silicon (a-Si) thin film with excimer laser and treated by PH
₃
gas plasma. With the TiO
₂
interface layer, the hydrogen response (
Sr
) of the n-LTPS Schottky diode under room temperature and -2-V bias is promoted from 331.5% to 3504% in 8000 ppm H
₂
/air ambient, which is comparable to the reported low cost H
₂
sensor based on bulk Si or III-V compound material. The hydrogen response promotion with the addition of the TiO
₂
layer is attributed to the suppression of the interface Fermi level pining issue and the increases of hydrogen adsorption activity.