First Principle Study Of The Electronic And Optical Properties Of Doped ZnTe

ZnTe is a typical Ⅱ-Ⅵ compound semiconductor which has great research value in the manufacture of optoelectronic devices and the application of solar cells because of its comparator large band gap, direct photon transition and heavy doping characteristics. In this paper, the electronic structures and optical properties of Cd/O, Al/N, Mn/O for codoped and I, In, Ag, B for single doped ZnTe were calculated using the first-principles plane-wave ultra-soft pseudo-potential method based on the density functional theory.It was found the bandgap of I doped ZnTe reduces and the Fermi level(EF) enters the valence band, it belongs to n-type doped, the optical absorption edges show red shift. The bandgap of In doped ZnTe increased and included a donor impurity level, the optical absorption edges show red shift, the ultraviolet region of the absorption coefficient is enhancement. To Ag doped ZnTe, the bandgap is slightly reduced, introducing impurity level in the forbidden band, since Ag was doped, the absorption coefficient in the ultraviolet region enhanced, the absorption in the visible range decreased; The calculated results showed that with the number of B atom doped ZnTe increase, the bandgap decreases, including a impurity level in the conduction band. To the optical properties:the3B doped ZnTe of absorption coefficient shows blue shift, and the absorption capability in the ultraviolet region was increased.It was found that the acceptor impurity levels of the valence band(VB) and donor impurity level of the conduction band(CB) were introduced into Cd/O codoped ZnTe, and the lattice mismatch is small, the lattice stability is good. To Al doped ZnTe, the conduction band(CB) almost coincides with the Fermi level(EF) which belongs to n-type doped, to N doped ZnTe, the Fermi level enters the valence band. The band gap greatly reduced of Al/N codoped ZnTe, and the optical absorption edges show red shift. The calculated results showed that the bandgap of Mn/O codoped ZnTe was increased, and many impurity bands appeared in the forbidden band which makes the transition energy of electrons absorb photons reduce and makes the optical absorption coefficient of the infrared region increase, due to due to the band gap increases, the absorption coefficient of intrinsic absorption region is reduced.