Hydrogen passivation studies on Pd–n-type-Si diodes

The effect of hydrogenation on the capacitance and the infrared absorption has been studied for a Pd–n-type-Si diode. The hydrogenation reduces the carrier density by approximately 30%. The infrared spectrum after hydrogenation shows the following changes: (i) A small peak near 2340±10 ${\mathrm{cm}}^{\mathrm{-}1}$ (corresponding to phosphorus-hydrogen bond) existing in the original sample grows and (ii) a new band near 2150–2050 ${\mathrm{cm}}^{\mathrm{-}1}$ appears (corresponding to silicon-hydrogen bond). The growth of the silicon-hydrogen band is faster than that of the phosphorus-hydrogen band. These results show that the hydrogen passivates the donor states through the formation of phosphorus-hydrogen and silicon-hydrogen (adjacent to the substitutional phosphorus) -like species.