Possible excited states in Si:Se and Si:Te prepared by femtosecond-laser irradiation of Si coated with Se or Te film

Abstract Se- and Te- doped silicon were prepared by irradiation of Si in the presence of Se and Te thin films, and then appropriate n+-n photodiodes were fabricated from the two materials. With I-V characteristics measurements, it is found that the Te doped diode exhibits smaller dark current and greater photocurrent compared with Se- doped diode. With Fourier-transform photoconductivity spectroscopy measurements, sub-bandgap photocurrent features are observed for Se- and Te- doped diodes. The optical activation energies for Si:Se are in good agreement with the known Se levels Se c 0 ( X 1 ) (116meV) and Se 2 + (390meV). The optical activation energies for Si:Te are in good agreement with the known Te levels T e + (411meV), Te c 0 ( X 1 ) (92meV), Te c + ( X 1 ) (364meV) and Te c + ( X 2 ) (173meV). The observed dopant centers in silicon facilitate the application of Si:Se and Si:Te in the sub-bandgap photoelectric devices.