Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 44: Poster Session I

HL 44.59: Poster

Tuesday, March 15, 2011, 18:00–21:00, P3

Thermal stability of ZnO/ZnCdO/ZnO double heterostructures — Martin Lange, •Anna Reinhardt, Christof P. Dietrich, Gabriele Benndorf, Michael Lorenz, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, Semiconductor Physics Group, Linnéstr. 5, D-04103 Leipzig, Germany

Band gap engineering is essential for the fabrication of efficient optoelectronic devices, which are based on heterostructures. For ZnO-based heterostructures, a material with a reduced bandgap is e.g. achieved by incorporation of Cd in ZnO.[1] As in the device fabrication, the behavior of the alloy during post-growth thermal processing is an important issue we studied the thermal stability of ZnO/ZnCdO/ZnO double heterostructures (Cd-DHS). The samples were grown by a pulsed laser deposition process on a-plane sapphire substrates using ZnO and CdO targets.[2] The Cd-DHS were annealed in air at temperatures from 620 ^∘C to 970 ^∘C to study their thermal stability.

Luminescence features of ZnO and ZnCdO where observed for the as-grown samples as well as for the annealed samples. Due to the annealing the ZnCdO-related luminescence exhibited a monotonic blue-shift with increasing annealing temperature. The underlying diffusion process, which explains the blue-shift, was investigated to determine the diffusion coefficient for the different annealing temperatures. The activation enthalpy of the diffusion coefficient was found to be between 2.1 eV and 3.5 eV, depending on the growth conditions.

[1] S. Sadofev et al., Appl. Phys. Lett. 89, 201907 (2006)

[2] M. Lange et al., J. Appl. Phys. 107, 093530 (2010)