Micro structures and Mechanical Characters of Hydrogenated Nanocrystalline Silicon Thin Films with Different Doped Proportions

摘要

Hydrogenated nanocrystalline silicon (nc-Si:H) films were deposited on glass substrates using Radio frequency plasma-enhanced chemical vapor deposition(RF-PECVD)from a B_2H_6/SiH_4/H_2 gas mixtures. In this paper, we mainly changed the Borane-Silane flow rate ratio (β), while other parameters were kept constant. Raman spectrum and X-ray diffraction were employed to investigate the micro-structure of the films, and the indentations were used to measure the mechanical characters (the Young's modulus (E) and hardness (H)). The Raman spectrum showed that, withβ increasing the crystalline fraction decreased, which indicated that more boron doped might not be propitious to the formation of crystalline of the thin films. XRD spectrum revealed that the films have a remarkably preferential orientation. The analysis of the Young's modulus and hardness by TriboIndenter nano system suggested that the increase in β had concernful effects in the decrease of E and H values, so we can control the mechanical characters of the thin films by means of changing the doped concentrations. In view of these results, it may be concluded that the use of low β conditions might lead to growth of nc-Si:H films with high crystallinity, and as well high Young's modulus and hardness.