X-ray photoelectron spectroscopy study of Sn+ implanted a-Si1 − xCx:H thin films

X-ray photoelectron spectroscopy was used to characterize a-Si1 − xCx:H thin films deposited by r.f. magnetron sputtering and implanted with Sn ions. Tin ion implantation results in modification of the optical band gap and absorption coefficient of a-Si1 − xCx:H films. The non-implanted films show the expected variety of chemical bonds: silicon-silicon and silicon-carbon bonds, carbon being three- and fourfold coordinated. The X0ray photoelectron and Raman spectra show that tin ion implantation leads to the introduction of additional disorder in the films. The X-ray photoelectron spectra of implanted films show that, in addition to already mentioned bonds, tin creates new bonds with the host elements, the nature of which depends on the depth. This chemical modification and additional disordering are the reasons for the observed in the optical properties of the films. A model based on the energy distribution of the implanted ions is proposed to explain the depth dependence of the nature of the chemical bonds which tin ions create during the implantation.