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First-Principle Calculation on the Electronic and Optical Properties of ZnO under the Loading

Author: LiLiXiang
Tutor: LiuRiPing
School: Yanshan University
Course: Materials Science
Keywords: ZnO First-principles calculations Stress-strain Band structure Optical Properties
CLC: TN304
Type: Master's thesis
Year: 2009
Downloads: 244
Quote: 1
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Abstract


The use of the CASTEP simulation software based on first-principles plane -wave pseudopotential method of ZnO in the hydrostatic pressure under uniaxial stress and the role of stress and strain introduced in the doping process electronic density of states , band structure , changes in the optical properties of were studied in detail . The results show that under the hydrostatic pressures d electronic density of states of major change with the change of ZnO coordination number , and the pressure has little influence . Polymorph of ZnO d electrons with the pressure increase is moved to a lower energy direction , but decreases with increasing coordination number , and to make changes in the band gap decreases pd repulsion ; the halite phase structure bimetal Areas under the action of the static pressure variable as a single metal area . About 2 GPa under uniaxial stress , the absolute value of the crystal field splitting energy reaches a minimum , limited uniaxial stress relaxation freer the top of valence band splitting intensifies, but does not change the nature of the direct band gap . Due to the anisotropy of the wurtzite ZnO , the polarization direction along the [100 ] direction of ZnO with uniaxial stress increases, the optical response peak is blue-shifted , but the optical response of peak intensity did not change significantly , while the [ 001 the polarization direction of the optical response strength greater impact . Effect on the strength of uniaxial stress on the optical response of the starting point is the most obvious , which comes mainly from the uniaxial stress for the valence band top structure , so that within the transition has greatly changed . The introduction of impurity atoms N , ZnO band gap decreases , N doped introduced stress value decreases ZnO lattice constants a and b , C value increases , the band gap increases , the N - doped ZnO grown in lattice constant on a smaller substrate , help to improve the solubility of N . N - doped ZnO with band gap along the [ 001 ] direction of the uniaxial stress increase linearly new optical response to the emergence of peak compressive stress .

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