Abstract
Heteroepitaxial zinc oxide (ZnO) films were grown on GaN templates by plasma-assisted molecular beam epitaxy. The epitaxial GaN templates were deposited by metalorganic chemical vapor deposition on c-plane sapphire substrates. Photoluminescence (PL) spectra of ZnO epilayers excited by a He-Cd laser exhibit only bound-exciton emission at 369 nm with phonon replicas at 10 K. The bound-exciton intensity of the ZnO epilayer grown under O-rich condition is five times greater than that of Zn-rich condition, indicating more non-radiative defects in the latter. High-intensity excitation PL was carried out using a N2 337-nm laser. The threshold of the emission from inelastic scattering between excitons is higher for Zn-rich-grown ZnO (68 kW/cm2) than for O-rich-grown ZnO (47 kW/cm2), indicating better optical quality for the latter. X-ray diffraction measurements show that there exists a residual compressive strain, ε=-0.25%, along the c-axis direction of the ZnO epilayer grown under Zn-rich condition.
Original language | English |
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Pages (from-to) | 133-136 |
Number of pages | 4 |
Journal | Journal of Crystal Growth |
Volume | 305 |
Issue number | 1 |
DOIs | |
State | Published - 1 Jul 2007 |
Keywords
- A1. Photoluminescence
- A1. Strain
- A1. XRD
- A3. P-MBE
- B2. ZnO