1. Sony Deutschland GmbH, Hedelfinger Strasse 61, D-70327 Stuttgart, Germany. Email: koch@sony.de
2. Fraunhofer Institute for Applied Solid-State Physics (IAF), D-79108 Freiburg, Germany
3. Sony Deutschland GmbH, Hedelfinger Strasse 61, D-70327 Stuttgart, Germany
4. Sony Corporation, 5-1-12 Kitashinagawa Shinagawa-ku, Tokyo, 141-0001, Japan