Empirical pseudopotential calculation of strain induced birefringence in ZnO


Empirical pseudopotential calculation of strain induced birefringence in ZnO

Fritsch, D.; Schmidt, H.

One big challenge in the fabrication of ZnO-based heterostructure devices is the lattice mismatch between ZnO films and substrates and the different thermal expansion coefficients inducing biaxial strain. There is currently also much interest in ZnO doped with 3d transition metal ions for spintroncis applications and the detection of ferromagnetic signatures by magneto-optical measurements of ordering induced birefringence being most intense around the critical point structure of the dielectric function. A quantitative understanding of Zeeman splitting far away from the center of Brillouin zone is still an open question and requires a separation of strain and magnetic field induced modifications of electronic band strcucture. We report on the effect of strain on the birefringence in ZnO films grown on Al2O3 or on SiC substrates. The imaginary part of the dielectric function has been calculated b means of the empirical pseudopotential method. Thereby we also accounted for relativistic effects in form of te spin-orbit interaction, for the energy-dependence of the crystal potential through the use of nonlocal model potentials, and for excitonic conrtibutions to the dielectric functiuon fue to discrete excitonic states and Coulomb enhanced band-to-band transitions.

Keywords: ZnO; birefringence

  • Poster
    72. Annual Meeting of the DPG and DPG Spring Meeting of the Condensed Matter Division, 25.-29.02.2008, Berlin, Germany

Permalink: https://www.hzdr.de/publications/Publ-11080
Publ.-Id: 11080