Consideration on Mobility Lowering Phenomenon in PolySi Films Using Tunneling Barrier Height Images

Polycrystalline silicon films were deposited on SiO2, and arsenic ions were implanted into these films. The Hall and resistivity measurements show that the mobility lowering effect and the activity lowering effect dominate the electrical properties of the films. Tunneling barrier height images also suggest carrier trapping at grain boundaries in lightly doped cases, indicating the possibility of arsenic segregation. These results indicate that the mechanism of the mobility lowering effect is mainly governed by the carrier trapping at grain boundaries.