XRD spectra of the four Gd doped samples compared with the XRD spectrum of an undoped ZnTe film grown under similar conditions. At the bottom is a schematic XRD of the zincblende structure ZnTe crystal for comparison.
XRD in the vicinity of the (311) peak of the four Gd doped ZnTe films as compared to the undoped film A. The vertical broken line shows the peak position of the undoped film.
(a) PT spectra of the undoped ZnTe film A compared with the Gd-doped ZnTe films. (b) Optical absorption spectra of the samples in the vicinity of the band gap.
Band gap and lattice constant of ZnTe films vs their [Gd] concentration.
A ball-and-stick model of the (a) lattice unrelaxed supercell containing only a substitutional Gd and (b) relaxed containing the defect pair compared with the corresponding unrelaxed supercell. The blue balls represent the Zn atoms, the golden balls represent the Te atoms, and the turquoise balls are the Gd atoms. The black balls in (a) represent the Te atoms which are removed in (b) to form the vacancies shown as the open spheres labeled . The parallelepiped shown by broken lines in (b) represents the primitive unit cell of . It is also shown in (a) where the unit cell is usually chosen to be a face-centered cube to highlight the lattice distortion after the introduction of the defect pair. The displacement of the individual balls can be followed by noting that corresponding atoms in the two figures have been labeled with the same number.
The band structure of ZnTe containing high concentration of (a) and (b) .
Band structures of (a) ZnTe containing high concentrations of compared with (b) ZnTe containing high concentration of .
Thickness and composition of four ZnTe samples doped with Gd. Sample A without Gd is our baseline.
Summary of total energy calculation results in ZnTe containing various point defects. The second row gives the formula of the supercell used in the calculation. is the band gap energy, and , the “optical band gap energy” including band-filling effect, is the energy for onset of absorption and can be compared with the band gap energy deduced from the PT spectra.
(A) Summary of total energy calculation results in ZnTe containing pairs of point defects. (B) Summary of total energy calculation results in ZnTe containing pairs of point defects.
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