Effects of iron impurities on the photoelectric response characteristics of silicon

Since Fe contamination is easily mixed into Si-based photoelectric materials during the fabrication process, the relative changes of energy levels and photoelectric properties of Si material mixed with Fe impurities in different occupancy sites are studied. Based on the first principle and photoelectric response theory, an analysis model of the response characteristics of Si material mixed with Fe impurities is established. The changes of the material's electronic structure are calculated, and the effects of different occupancy sites of Fe impurities on the photoelectric response characteristics of materials are comparatively analyzed. Results show that when the Fe atom occupies the tetrahedral interstitial site in Si, the energy band structure and response characteristics of the material are relatively obviously affected. In this case, the impurity energy band introduced by the Fe impurity passes through the Fermi level, leading to the disappearance of the band gap. The absorption of Si material outside the response band is significantly enhanced. And a new absorption peak is generated at about 1530nm, with an absorption coefficient of about 25513 cm-1. Thus, the Si material can produce a relatively strong response to the light beam outside the response band. In the meantime, the saturation threshold of the Si-based photoreceptor is significantly lower than that of the other two position types. For the irradiation light at the wavelength of 1319nm, the saturation power is only 0.0035 W∙cm-2. The analysis results provide a reference for the application and development of photoelectric devices.