Determination of the optical parameters of a-Si:H thin films deposited by hot wire–chemical vapour deposition technique using transmission spectrum only

Pramana

S R Jadkar3³  V S Waman¹  R R Hawaldar²  M M Kamble¹  S W Gosavi³  Nabeel A Bakr¹  D P Amalnerkar²  A M Funde¹ 

[1] School of Energy Studies, University of Pune, Pune 411 007, India$$;Centre for Materials for Electronics Technology (C-MET), Panchawati, Pune 411 008, India$$;Department of Physics, University of Pune, Pune 411 007, India$$

关键词: Hydrogenated amorphous silicon (a-Si:H);    optical properties;    UV–visible spectroscopy;    refractive index;    dielectric constant.;   

DOI  :  

学科分类：物理（综合）

来源: Indian Academy of Sciences

【 摘 要 】

Three demonstration samples of intrinsic hydrogenated amorphous silicon (a-Si:H) films were deposited using hot wire–chemical vapour deposition (HW–CVD) technique. The optical parameters and the thickness were determined from the extremes of the interference fringes of transmission spectrum in the range of 400–2500 nm using the envelope method. The calculated values of the refractive index (𝑛) were fitted using the two-term Cauchy dispersion relation and the static refractive index values (𝑛0) obtained were 2.799, 2.629 and 3.043 which were in the range of the reported values. The calculated thicknesses for all samples were cross-checked with Taly-Step profilometer and found to be almost equal. Detailed analysis was carried out to obtain the optical band gap (𝐸g) using Tauc’s method and the estimated values were 1.99, 2.01 and 1.75 eV. The optical band gap values were correlated with the hydrogen content (𝐶H) in the samples calculated from Fourier transform infrared (FTIR) analysis. An attempt was made to apply Wemple–DiDomenico single-effective oscillator model to the a-Si:H samples to calculate the optical parameters. The optical band gap obtained by Tauc’s method and the static refractive index calculated from Cauchy fitting are in good agreement with those obtained by the single-effective oscillator model. The real and the imaginary parts of dielectric constant (𝜀r, 𝜀𝑖), and the optical conductivity (𝜎) were also calculated.

【 授权许可】

Unknown