Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 2: Symposium ZnO - Rediscovered

HL 2.4: Vortrag

Freitag, 4. März 2005, 12:15–12:45, TU P270

Microscopic Luminescence Properties of ZnO and ZnO based Heterostructures — •Jürgen Christen and Frank Bertram — Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, PSF 4120, Magdeburg, D-39016, Germany

ZnO has re-emerged into the center of international attention. Although know for many years, there is still a lack of information on its microstructure and in particular its microscopic electronic and optical properties. We present spatially resolved luminescence investigations directly correlating the optical characteristics to the nano-scale morphology. The strong impact of local internal fields (Franz-Keldysh-Effect) is evidenced. Expected for hetero-interfaces (spontaneous / piezo-polarization), this is also found at homo-interfaces and even in ZnO single crystals at domain boundaries. In epitaxially grown Zno films, a direct correlation between defects and morphology and specific spectral features is found. The bound exciton luminescence I8 directly images the dislocation network and its spectral position maps the lateral strain profile. A selective incorporation of those impurities associated with I0 and I1 at the micro-domain boundaries is evidenced. The situation further complicates when adding ternary alloys such as MgZnO or CdZnO, needed for heterostructures and Quantum Wells. A one-by-one correlation of local stoicheometry and micro-morphology as well as its impact on the relaxation and recombination kinetics is presented.