Influence of Ar/H2 ratio on the characteristics of boron-doped nc-Si:H films prepared by electron cyclotron resonance plasma-enhanced chemical vapor deposition

Boron-doped hydrogenated nanocrystalline silicon (nc-Si(B):H) films were prepared by electron cyclotron resonance plasma-enhanced chemical vapor deposition (ECR-PECVD). The effect of Ar/H2 ratio on the characteristic of as-grown nc-Si(B):H films was investigated systematically with Raman scattering, XRD, XPS as well as Hall effect measurements. The experimental results indicate that the increase of Ar/H2 ratio can enhance the concentration of B in the as-grown films. On the other hand, with the Ar/H2 ratio increasing, the crystallinity of the films deteriorated sharply, and the electrical properties of the as-grown films decreased. Langmuir Probe was used to investigate the electron temperature (Te) of microwave activated B2H6/Ar/H2 plasmas. Finally, the microscopic mechanism of the enhancement in doping efficiency was elucidated in terms of the plasma reaction equations of B2H6 and Langmuir probe testing result.

► We investigated the influence of Ar/H2 ratio on the characteristics of B-doped films.
► Diluting process gas H2 with Ar did enhance the doping amount of B2H6 in the films.
► The crystallinity of the films decreased intensively with Ar/H2 ratio increasing.
► The microscopic mechanism of the enhancement in doping efficiency was elucidated.