This paper reports that high-rate-deposition of microcrystalline silicon solar cells was performed by very-highfrequency plasma-enhanced chemical vapor deposition.These solar cells,whose intrinsic μc-Si:H layers were prepared by using a different total gas flow rate (F total),behave much differently in performance,although their intrinsic layers have similar crystalline volume fraction,opto-electronic properties and a deposition rate of ～ 1.0 nm/s.The influence of F total on the micro-structural properties was analyzed by Raman and Fourier transformed infrared measurements.The results showed that the vertical uniformity and the compact degree of μc-Si:H thin films were improved with increasing F total.The variation of the microstructure was regarded as the main reason for the difference of the J-V parameters.Combined with optical emission spectroscopy,we found that the gas temperature plays an important role in determining the microstructure of thin films.With F total of 300 sccm,a conversion efficiency of 8.11% has been obtained for the intrinsic layer deposited at 8.5 A/s (1 A=0.1 nm).
In this paper, a series of boron doped microcrystalline hydrogenated silicon-germanium (p-μc-Si1-xGex:H) was deposited by very high frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) from SiH4 and GeF4 mixtures. The effect of GeF4 concentration on films' composition, structure and electrical properties was studied. The results show that with the increase of GeF4 concentration, the Ge fraction x increases. The dark conductivity and crystalline volume fraction increase first, and then decrease. When the GC is 4%, p-μc-Si1-xGex:H material with high conductivity, low activation energy (σ = 1.68 S/cm, Eg = 0.047 eV), high crystalline volume fraction (60%) and with an average transmission coefficient over the long wave region reaching 0.9 at the thickness of 72 nm was achieved. The experimental results were discussed in detail.
