Influence of the thickness of Si and Ge films deposited on SiN/SiO/Si substrates on their structure and diffusion of hydrogen atoms from SiN layers
arXiv:2201.04948
Abstract
The results of RHEED, FTIR and Raman spectroscopy study of silicon and germanium films with the thickness up to 200 nm grown from molecular beams on dielectric SiN/SiO/Si(001) substrates are presented. Noticeable changes of the intensity of the NH and SiN absorption bands have been observed in the IR absorbance spectra as a result of the deposition of the silicon and germanium films. The thicker was the deposited film, the more considerable were the decrease of NH absorption band intensity and the increase in that of the SiN band. This tendency has been observed during the growth of both amorphous and polycrystalline Si or Ge films. The reduction of IR absorption at the band assigned to the NH bond vibration is explained by breaking of these bonds followed by the diffusion of the hydrogen atoms from the SiN layer into the growing film of silicon or germanium. The effect of the deposited film thickness on the diffusion of hydrogen is discussed within a model of the diffusion of hydrogen atoms controlled by the difference in chemical potentials of hydrogen atoms in the dielectric SiN layer and the growing silicon or germanium film. Hydrogen atoms escape from the SiN layer only during the deposition of a Si or Ge film when its thickness gradually grows. The interruption of the film growth stops the migration of hydrogen atoms into the film because of the decline in the chemical potential difference.
45 pages, 17 figures