Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 19: Silicon and Germanium

HL 19.1: Talk

Monday, March 14, 2011, 14:30–14:45, POT 251

Phase Separation and Size Controlled Nanocrystal Formation in GeO — •Christoph Sahle¹, Christian Sternemann¹, Alexander Nyrow¹, Alexander Schwamberger¹, Florian Wieland¹, Manuel Zschintzsch², Johannes Borany², Achim Hohl³, and Metin Tolan¹ — ¹Fakultät Physik/DELTA Technische Universität Dortmund, Otto-Hahn-Straße 4, 44227 Dortmund, Germany. — ²Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf e.V., P.O. Box 510119, 01314 Dresden, Germany. — ³Institute for Materials Science, Darmstadt University of Technology, 64287 Darmstadt, Germany.

Semiconducting group IV nanocrystals (NC), such as Ge- and Si-NC, have drawn a lot of attention in recent years because of their potential use in new generations of light emitting diodes, fast and stable non-volatile flash memories or highly efficient solar cells. Although intensive research has been conducted regarding the photoluminescence and charge storage properties of readily produced oxide embedded NCs little is known about the phase separation and NC formation process. Here, we present in and ex situ X-ray absorption near edge structure (XANES) spectroscopy data of the temperature induced disproportionation, i.e phase separation of GeO_x (x ≈ 1) into Ge and GeO₂, which leads to the formation of Ge NCs embedded in a Ge oxide matrix. The formation of size controlled Ge NCs is achieved using a GeO_x–SiO₂ superlattice approach. The influence of reducing hydrogen in the annealing ambient on the phase separation process and resulting NC density is discussed.