Ion-beam hydrogenation of sputter-deposited amorphous silicon and amorphous silicon-germanium alloys

The posthydrogenation of undoped and boron-doped amorphous silicon and amorphous silicon-germanium alloys was studied using a Kaufman ion-beam source. These materials were deposited in a two-source radio frequency (RF) excited argon plasma sputter-deposition system. After ion-beam posthydrogenation, the optical bandgap of amorphous silicon-germanium alloys increased from about 1.12 eV to 1.47 eV, and the material has an air mass one photosensitivity of 1.5×10³ . The conductivity of the boron-doped amorphous silicon material improved by more than two orders of magnitude after ion-beam posthydrogenation. The material-removal rate during ion-beam hydrogenation is more sensitive to the ion-beam current density than to the ion-beam energy. The hydrogen content of ion-beam hydrogenated samples is about 30 at.% at the front surface and decreases exponentially toward the back surface tip to about 100 nm from the front surface