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HL: Fachverband Halbleiterphysik

HL 78: Quantum dots: Preparation and characterization

HL 78.3: Vortrag

Mittwoch, 2. April 2014, 17:00–17:15, POT 251

Crystallization phenomena of germanium nano crystals in ZrO₂ — •Maximilian Geyer¹, Peter Seidel¹, David Lehninger¹, Volker Klemm², Gerhard Schreiber², and Johannes Heitmann¹ — ¹TUBAF, Institut für Angewandte Physik — ²TUBAF, Institut für Werkstoffwissenschaften

Due to the heightened interest of semiconductor nanocrystals in high-κ matrices the crystallization of germanium in ZrO₂ was investigated. Germanium was especially interesting because of its smaller band gap and higher Bohr-radius then silicon and ZrO₂ shows superior high-κ and dielectric properties and is of interest for optical and electrical applications.

All samples were prepared by a co-sputtering process of a superlattice containing pure ZrO₂ and mixed Ge/ZrO₂ layers. First different annealing processes combined with different capping layers to prevent the oxidation of germanium due to the oxygen conductivity of the matrix were tested. A Capping layer of SiO₂ combined with a RTP annealing process gives the best results. Raman and photoluminescence spectroscopy show characteristic peaks after this processing which are connected to nanocrystalline structures.

Furthermore we found that a interface layer of silicon nitride in contrast to the natural silicon oxide transmits the crystal information of our silicon substrate to the layers of our superlattice and makes a continuous crystallization of germanium possible.

Further research will investigate different layer compositions and the possibility of lateral conductivity through the nano crystalline layers.