Regensburg 2004 – scientific programme
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HL: Halbleiterphysik
HL 21: II-VI Halbleiter II
HL 21.3: Talk
Tuesday, March 9, 2004, 15:45–16:00, H13
Microscopic Spatial Distribution of bound excitonic luminescence in high-quality ZnO — •Daniel Forster, Frank Bertram, Jürgen Christen, Nikolay Oleynik, Armin Dadgar, and Alois Krost — Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Germany
ZnO has received much attention as a material for opto-electronic devices because of its direct wide band gap and high exciton binding energy. The ZnO epitaxial layers investigated were grown by MOCVD on 1µm thick GaN layers on sapphire template using a two step growth process: First, a low-temperature ZnO buffer was deposited at 450∘C. In the second step, a high-temperature ZnO layer was grown above 800∘C. This final ZnO layer exhibits supreme crystalline and optical quality. Using highly spatially and spectrally resolved cathodoluminescence (CL) microscopy a direct correlation of the structural and the optical properties of these ZnO sandwich layers has been achieved on a microscopic scale. The laterally integrated spectrum of each sample is dominated by narrow (<1.3 meV) I8 [1] luminescence from the surface. Local spectra taken at the edges of domains show a pronounced emission line at I0,I1 [1], whereas inside of the domains no enhanced intensity in this spectral region is found. Monochromatic images prove a selective incorporation of impurities at the grain boundaries of the growth domains. [1] N. Presser, J. Gutowski, I. Broser, Phys. Rev. B36, 9746 (1988).