Enhanced photoconductivity of 3C-SiC by Al/N codoping

Abstract

In order to enhance the photoconductivity of 3C-SiC by high Al doping, the Al/N codoping has been investigated using the first principles calculation. Several structural models were constructed, i.e., Al1/N, Al2/N, Al3/N, and Al4/N. Structural stability and electronic property of Al/N codoped 3C-SiC with different models were studied. It is found that the adjacent pair of Al and N in 3C-SiC is energetically favorable, and the structure of Al/N codoped 3C-SiC is more stable than that of the mono Al doped 3C-SiC. The results indicate that the N incorporation facilitates the substitution of Al for Si in 3C-SiC. The mono doping of Al can cause the band gap decrease by 82 meV. However, the codoping of Al and N can further narrow the band gap by 167 meV. Photoconductivity calculation shows the photoconductivity of the Al/N codoped 3C-SiC is higher in the range from near infrared to ultraviolet wavelength in comparison with the intrinsic 3C-SiC. The calculated intrinsic absorption edge of Al/N codoped 3C-SiC shows a red-shift in ultraviolet region with respect to that of Al doped 3C-SiC. The electron density difference of Al/N codoped 3C-SiC indicates the bond between Al and C has stronger covalent characteristics than that between Al and N. The calculations suggest the Al/N codoped 3C-SiC semiconductor as a promising material for device applications in modern electronics.