| Due to its excellent photoelectric properties,ZnTe has broad application prospects in blue and green light devices,solar cells and other fields.Based on first principles,this paper studied the different concentrations of A1 and Sb doping on the properties of ZnTe photoelectric effect,the conductive type of n-type and p-type ZnTe material,by doping control of band gap and the intensity of light absorption ZnTe material to improve the photoelectric performance,to make more efficient ZnTe base p-n junction and CdTe thin film solar cells back contact layer has important theoretical value.The research contents are as follows:1.The electrical properties of pure ZnTe and Al-doped ZnTe with different concentrations were calculated.The results show that the band gaps of pure ZnTe and Al-doped ZnTe at 3.13%,6.25%and 12.50%concentration are 1.10eV,0.91eV,0.85eV and 0.81eV,respectively.Indicating that the band gaps of the doped system decreased gradually with the increase of Al doping concentration.In addition,the Fermi level of the three doping systems is located at the CBM(Conduction Band Minimum),and an impurity level appears at the CBM,thus obtaining n-type semiconductor materials with conductive type.2.The optical properties of pure ZnTe and Al-doped ZnTe with different concentrations were calculated.The results show that the absorption band edges of pure ZnTe and three Al-doped systems are 2.2eV,1.8eV,1.7eV and 1.6eV,respectively,indicating that with the increase of doping concentration,the absorption band edges of the system have different degrees of red shift to the lower energy direction compared with pure ZnTe,and the absorption wavelength of the system has widened to the red band.In addition,with the increase of doping concentration,the absorption of light in the visible region of the system is strengthened,and n-type semiconductor with higher light absorption efficiency is obtained,which has important theoretical value for the production of ZnTe based p-n junction with higher photoelectric conversion efficiency.3.The electrical properties of Sb-doped ZnTe with different concentrations were calculated.The results show that the band gap widths of Sb-doped ZnTe with 3.13%,6.25%and 12.50%are 0.89eV,0.75eV and 0.64eV,respectively.Compared with the pure ZnTe,the band gap values of Sb-doped ZnTe with 3.13%,6.25%and 12.50%are decrease,and their band gap values gradually decrease with the increase of doping concentration.It is also indicated that Sb-doped ZnTe is an effective means to regulate the band gap of ZnTe.In addition,there are several impurity levels in the valence band tops of the three doping systems,which still belong to p-type semiconductor.Due to the appearance of impurity level and the reduction of band gap width,the electron transition of doping system is easier,which is of great value for the fabrication of more efficient optoelectronic devices.4.The optical properties of Sb-doped ZnTe with different concentrations were calculated.The results show that the absorption band edges of ZnTe with 3.13%,6.25%and 12.50%Sb doping are 1.8eV,1.5eV and 1.3eV,respectively.With the increase of Sb doping concentration,the absorption band edges of the system gradually redshift to the direction of low energy,and the absorption wavelength of the system broadened to the red band and longer band.Especially,the absorption wavelength of the system with doping concentration of 12.50%reaches 954nm,and the absorption range extends to the near-infrared band.Like the Al-doped system,with the increase of doping concentration,the absorption of light in the visible region of Sb-doped system is also enhanced.Sb doping not only effectively improves the light absorption capacity of ZnTe,but also widens the light absorption range of the material,thus obtaining p-type semiconductor materials with higher light absorption efficiency.As an excellent back contact layer of CdTe thin-film solar cells,the doping material has more excellent light absorption capacity,which is of great significance to improve the photoelectric conversion efficiency of CdTe thin-film solar cells. |
PDF Full Text Request