Regensburg 2007 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 38: ZnO I
HL 38.6: Talk
Thursday, March 29, 2007, 11:15–11:30, H17
Cathodoluminescence study of ZnO and Zn1−xMgxO nanopillars on different substrates — •Martin Schirra, Anton Reiser, Raoul Schneider, Günther Prinz, Klaus Thonke, and Rolf Sauer — Institut für Halbleiterphysik, Universität Ulm, D-89069 Ulm
ZnO nanopillars are potential candidates for future sensor and optoelectronic devices. Any application calls for optimal structural and optical properties of such pillars. In the present study single nanopillars, mainly grown by the vapor-liquid-solid process, were investigated by spatially resolved cathodoluminescence in a scanning electron microscope (SEM-CL) at low temperatures (10K) and low acceleration voltages (2kV).
In order to achieve at the same time high SEM resolution and CL sensitivity, a new concept was realized based on a field-emitter type SEM and light collection by a glass fiber. ZnO nanopillars on sapphire substrate exhibit free and bound exciton recombination with narrow linewidths indicating high purity and high crystal quality. ZnO nanopillars on a GaN template show broad luminescence in the near-band edge region due to the incorporation of Ga into the pillars. Corresponding Ga concentrations are estimated. Nanopillars grown homoepitaxially on a ZnO thin film show mainly two donor bound exciton lines with narrow linewidths which are presumably related. Ternary Zn1−xMgxO nanopillars are also grown by the vapor-liquid-solid process. Incorporation of Mg into the ZnO matrix is demonstrated by blue-shifts of the luminescence, and the Mg concentration is determined.