- Email: [email protected]
Self-organization in semiconductors—fundamentals and applications
Materials Science and Engineering B88 (2002) 111
www.elsevier.com/locate/mseb
Editorial
Self-organization in semiconductors —fundamentals and applications
Self-organization is a quite universal phenomenon in material science. The formation of natural superlattices resulting in ‘polytypes’ (e.g. ZnS or SiC) has been known for a long time. In recent years, natural superlattice ordering during epitaxial growth of compound semiconductor alloys (e.g. in In0.5Ga0.5P) has found much attention. Whereas this type of self-organization still results in three-dimensionally periodic structures (limited only by domain formation), self-organization in the form of island growth leads to compositional non-uniformities, which may still preserve the topology of the lattice of the host material (e.g. pseudomorphically strained self-assembled InAs quantum dots, or ErAs island layers in GaAs). Finally, precipitates in the form of self-organized nanosize clusters exhibiting a different crystal structure, are observed in many nonequilibrium systems (e.g. metallic As clusters in annealed ‘low-temperature-grown GaAs’, ferromagnetic clusters formed by annealing of MnGaAs layers). All these self-organized systems have in common a (nearly) perfect overall crystalline order of the host material. They have found wide interest due to their unique electrical (e.g. semi-insulating), magnetic (single-domain nano-ferromagnets) and optical (e.g. polarization anisotropy) features, due to changes of the crystal symmetry, reduced dimensionality (e.g. self-assembled quantum dots as ‘model atoms’), which are very promising for a wide range of applications (e.g. single electron electronics, novel non-volatile memories). A common goal of all researchers in the field of self-organizing systems, whether primarily interested in systematic investigations of the specific material properties or in the applications, is the ‘taming of the self-organization’. This term means getting control of the self-organization by influencing the period of polytypes, the size of ordered domains, islands or clusters, arranging them in 1-, 2- or 3-dimensional periodic arrays… However, our present understanding of the phenomenon of self-
organization, which is a prerequisite to attaining this goal, is still rather scarce. The goal of the symposium on ‘Self-organization in Semiconductors —Fundamentals and Applications’ was to gather scientists working on the various systems exhibiting self-organization for having an in-depth discussion of the various mechanisms, and also of the properties of the self-organized structures and their implications for device applications. This volume is a collection of (most of) the invited and the contributed papers presented at this symposium, which was part of the E-MRS 2001 Spring Meeting in Strasbourg (France). I think this synopsis documents quite well that the goal of the symposium has been largely met. More important, I hope it will represent a valuable source of information for those who are fascinated by the phenomena of self-organization. At this time I would like to thank the co-organizers of the symposium, Jo De Boeck, Alain Claverie, Arthur C. Gossard, and Venkatesh Narayanamurti for their invaluable help in putting together an interesting program, the invited and contributing colleagues for providing a written version of their presentations, and to Larry Cooper from the Office of Naval Research for financial support for the symposium. Last, but not the least, I would like to acknowledge the great help of my secretary, Mrs Kerstin Rossmeisel, in the procedure of finalizing the material for the publication.
0921-5107/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 5 1 0 7 ( 0 1 ) 0 0 8 6 0 - 1
Gottfried H. Do¨hler Institut fu¨r Technische Physik I, Friedrich-Alexander-Uni6ersita¨t, Erlangen-Nu¨rnberg, Erwin-Rommel-Straße 1, 91058 Erlangen, Germany E-mail: [email protected]
www.elsevier.com/locate/mseb
Editorial
Self-organization in semiconductors —fundamentals and applications
Self-organization is a quite universal phenomenon in material science. The formation of natural superlattices resulting in ‘polytypes’ (e.g. ZnS or SiC) has been known for a long time. In recent years, natural superlattice ordering during epitaxial growth of compound semiconductor alloys (e.g. in In0.5Ga0.5P) has found much attention. Whereas this type of self-organization still results in three-dimensionally periodic structures (limited only by domain formation), self-organization in the form of island growth leads to compositional non-uniformities, which may still preserve the topology of the lattice of the host material (e.g. pseudomorphically strained self-assembled InAs quantum dots, or ErAs island layers in GaAs). Finally, precipitates in the form of self-organized nanosize clusters exhibiting a different crystal structure, are observed in many nonequilibrium systems (e.g. metallic As clusters in annealed ‘low-temperature-grown GaAs’, ferromagnetic clusters formed by annealing of MnGaAs layers). All these self-organized systems have in common a (nearly) perfect overall crystalline order of the host material. They have found wide interest due to their unique electrical (e.g. semi-insulating), magnetic (single-domain nano-ferromagnets) and optical (e.g. polarization anisotropy) features, due to changes of the crystal symmetry, reduced dimensionality (e.g. self-assembled quantum dots as ‘model atoms’), which are very promising for a wide range of applications (e.g. single electron electronics, novel non-volatile memories). A common goal of all researchers in the field of self-organizing systems, whether primarily interested in systematic investigations of the specific material properties or in the applications, is the ‘taming of the self-organization’. This term means getting control of the self-organization by influencing the period of polytypes, the size of ordered domains, islands or clusters, arranging them in 1-, 2- or 3-dimensional periodic arrays… However, our present understanding of the phenomenon of self-
organization, which is a prerequisite to attaining this goal, is still rather scarce. The goal of the symposium on ‘Self-organization in Semiconductors —Fundamentals and Applications’ was to gather scientists working on the various systems exhibiting self-organization for having an in-depth discussion of the various mechanisms, and also of the properties of the self-organized structures and their implications for device applications. This volume is a collection of (most of) the invited and the contributed papers presented at this symposium, which was part of the E-MRS 2001 Spring Meeting in Strasbourg (France). I think this synopsis documents quite well that the goal of the symposium has been largely met. More important, I hope it will represent a valuable source of information for those who are fascinated by the phenomena of self-organization. At this time I would like to thank the co-organizers of the symposium, Jo De Boeck, Alain Claverie, Arthur C. Gossard, and Venkatesh Narayanamurti for their invaluable help in putting together an interesting program, the invited and contributing colleagues for providing a written version of their presentations, and to Larry Cooper from the Office of Naval Research for financial support for the symposium. Last, but not the least, I would like to acknowledge the great help of my secretary, Mrs Kerstin Rossmeisel, in the procedure of finalizing the material for the publication.
0921-5107/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 5 1 0 7 ( 0 1 ) 0 0 8 6 0 - 1
Gottfried H. Do¨hler Institut fu¨r Technische Physik I, Friedrich-Alexander-Uni6ersita¨t, Erlangen-Nu¨rnberg, Erwin-Rommel-Straße 1, 91058 Erlangen, Germany E-mail: [email protected]