Future Trends in Microelectronics: Up the Nano Creek

Formation of Three-Dimensional SiGe Quantum Dot Crystals

C. Dais, P. Käser, H. Solak, Y. Ekinci, E. Deckhardt, E. Müller, D. Grützmacher

Laboratory for Micro- and NanotechnologyPaul Scherrer Institute, Villigen, Switzerland

J. Stangl, T. Suzuki, T. Fromherz, and G. Bauer

Inst. für Halbleiter und FestkörperphysikJohannes Kepler University Linz, A-4040 Linz, Austria

1.   Introduction

Silicon based quantum dot materials are gaining attention due their potential for ultimate CMOS devices¹ or for beyond-CMOS device architectures.^2-4 Germanium dots incorporated in Si are particularly promising because their fabrication can take advantage of the well-developed Si technology. The long spin coherence times in Si^5-7 represent another advantage of this material system, opening possible routes towards spintronics and quantum computation. The embedding of individually addressable Ge quantum dots into Si device technology might be crucial to open new paths for the fabrication of high speed electronics. Self-assembled Ge dots, which nucleate randomly on the surface and have typically a rather broad distribution in their sizes, have been studied intensively. Across a large window in deposition temperature a bimodal distribution of Ge islands is found, with small Ge huts coexisting with large Ge dome clusters.⁸ However, many proposed devices, like the dot-FET⁹ or dot arrays for qubit information technology,^2-4 require a uniform size distribution. Moreover, the addressing of individual dots will ...