Effect of Hydrogen Gas Conditions on the Structural, Optical, and Electronic Features of nc-Si:H Thin Films

Abstract

Hydrogenated nanocrystalline Si (nc-Si: H) films were prepared by plasma enhanced chemical vapor deposition using SiH4/H2 gas. The Si nanocrystallites of the films consisted of Si–Hn (n = 1, 2, 3) bonds. The relative fraction of the Si–H bonds affected the size and volume fraction of the crystallites. Hydrogen radicals are essential for the formation of Si nanocrystallites. The Si nanocrystallite size increased from ~ 2.0 to ~ 3.0 nm with an increase in the H2 flow rate from 60 to 90 sccm. At the H2 flow rate of 90 sccm, the film became completely polymeric consisting mainly of Si–H-type bonds.