Temperature dependence of electron-capture cross section of localized states ina−Si:H

A temperature dependence of the electron-capture cross section [${\sigma }_n\mathrm{}(E,T)\mathrm{}$] of the gap states in $a-\mathrm{S}\mathrm{i}:\mathrm{H}$ was determined for the first time by isothermal capacitance transient spectroscopy. A bump was observed on the gap-state profile of lightly P-doped $a-\mathrm{S}\mathrm{i}:\mathrm{H}$ and ${\sigma }_n\mathrm{}(E,T)\mathrm{}$ increases as temperature increases. From this temperature dependence as well as the energy dependence of ${\sigma }_n\mathrm{}(E,T)\mathrm{}$ reported previously, it is concluded that the bump of gap-state profile is located approximately 0.5 eV below the conduction-band mobility edge and multiphonon emission predominates in the electron-capture process at the gap states near the bump. It is strongly suggested that the bump structure originates from doubly occupied dangling-bond states.