Influence of hydrogen dilution on structural, electrical and optical properties of hydrogenated nanocrystalline silicon (nc-Si:H) thin films prepared by plasma enhanced chemical vapour deposition (PE-CVD)

摘要: Abstract Hydrogenated nanocrystalline silicon (nc-Si:H) thin films were deposited from pure silane (SiH4) and hydrogen (H2) gas mixture by conventional plasma enhanced chemical vapour deposition (PE-CVD) method at low temperature (200 °C) using high rf power. The structural, optical electrical properties of these are carefully systematically investigated as a function dilution (R). Characterization with angle X-ray diffraction Raman spectroscopy revealed that the crystallite size in tends to decrease same time volume fraction crystallites increases increase R. Fourier transform infrared (FTIR) spectroscopic analysis showed values R, is predominantly incorporated nc-Si:H mono-hydrogen (Si H) bonding configuration. However, increasing R shifts di-hydrogen H2) H2)n complexes. content decreases was found less than 10 at% over entire studied range On other hand, Tauc's band gap remains 2 eV or much higher. quantum effect may responsible for higher films. A correlation between structural has been found. For optimized conditions, ∼7.67 nm having good degree crystallinity (∼84% ) (2.25 eV) obtained (6.5 at%). rate quite small (1.6 A/s).