Effect of substrate temperature on the nanostructural and chemical features of nc-Si:H thin films prepared by PECVD

摘要

Hydrogenated nanocrystalline silicon (nc-Si:H) thin films were deposited by plasma enhanced chemical vapor deposition (PECVD) at a RF power of 100 W; SiH_4 and H_2 were introduced into a reaction chamber at 25 and 40 sccm, respectively, and the substrate temperature ranged from room temperature to 600 °C. The effect of the substrate temperature on the formation of nanoscale Si crystallites (nc-Si) and their structural and optical features were investigated. The average size and concentration of the Si nanocrystallites varied with the substrate temperature; the former ranged from ～1.0 to ～5.0 nm, and the latter reached up to ～15.5% when the substrate temperature was 400 °C. With increasing substrate temperature to 400 °C, the relative fraction of Si-H bonds in the films, [Si-H]/∑n=13[Si-Hn]n=integer, was increased up to ～29.3%.