The Effect Of Nitrogen And Phosphorus Doping On Optical Properties Of 3C-SiC

Silicon carbide (SiC) is the semiconductor of wide band-gap, large thermal conductivity, high break down field, high saturation rate, and smaller dielectric constant. These properties make SiC suitable for high-power, high-temperature, and high frequency electronic devices. However, due to its indirect band gap characteristic, the photoelectric conversion efficiency is very low. Therefore, how to improve luminous efficiency is an important issue for the research of SiC. In recent years, a large number of experiment and theoretical studies prove that the properties of SiC materials can be controlled through the incorporation of impurity,which will increase the luminous efficiency of SiC. This paper numerically studies the band structure and optical properties for undoped and doped 3C-SiC, and the photoconduction and photoluminescence properties are also investigated. The mechanism effects on photoconductive properties and the factor effects on photoluminescence have been mainly researched. The major work we have done is as follows:Firstly, research status and development trends of SiC are clarified, and the signification of this paper work is put forward. The structures, fundamental characteristics of SiC, device technology and research and application prospects are introduced.Secondly, we simply explain the basic framework and development of the density functional theory, and introduce the characteristics of software CASTEP.Thirdly, the first-principles method is employed to investigate the band structure and conductivity spectra. According to semiconductor theory, the scattering mechanisms are calculated to explore the conductive properties. The analysis shows that the neutral impurity scattering and inter-carrier scattering are the main mechanisms for conduction behavior. But in the UV region, long-wavelength optical wave scattering is the main reason for the anomalous conductivity.Finally, using the radiative recombination luminescence and the first-principles density functional theories, we investigated the photoluminescence spectra of doped 3C-SiC. The results show that because the band gap of 3C-SiC from indirect band gap into direct band gap, the carrier concentration increase near the Fermi level. Thus, photoluminescence strength greatly is increased. But, PL peak is connect with the absorption peak.