Electrical and structural properties of low temperature boron- and phosphorus-doped polycrystalline silicon thin films prepared by ECR-CVD

Effects of high hydrogen dilution on the optical and electrical properties in B-doped nc-Si:H thin films

“…Analogous to Ref. [33], the competition of two mechanisms (i.e., impurity scattering effect and crystallinity) proposed below can explain the Hall mobility behavior very well. The carrier concentration increases rapidly due to the increase of doping efficiency and impurity concentration added into nc-Si:H. And the more impurity atoms in the nc-Si:H films, the stronger effect of impurity scattering which includes both the ionized and neutral impurity scattering [34], leading to the decrease of mobility.…”

“…We find that the carrier concentration increases from 0.69 Â 10 20 to 4.70 Â 10 20 cm À3 when the H 2 /SiH 4 ratio increases from 62.5 to 142.9. That is probably due to the function of the atomic hydrogen that not only enhances the surface diffusion length, but also plays the role of structure relaxation through the penetration into subsurface and weak-bonds-breaking effect, as mentioned in boron-doped poly Si [33]. (The details will be discussed in the later part of the growth mechanism.)…”