Density of states of superlattices with multiple layers per period |
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| Authors: | R Kucharczyk M St
licka B Brzostowski B Djafari-Rouhani |
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| Institution: | 1. Institute of Experimental Physics, University of Wrocław, plac Maksa Borna 9, 50-204 Wrocław, Poland;2. Laboratoire de Dynamique et Structure des Matériaux Moléculaires, U.R.A. C.N.R.S. No. 801, U.F.R. de Physique, Université de Lille I, 59655 Villeneuve d''Ascq Cedex, France;1. Institute for Nanoscale Technology, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia;2. Australian Institute for Bioengineering and Nanotechnology, University of Queensland, QLD 4072, Australia;3. Centre for Advanced Imaging, University of Queensland, QLD 4072, Australia;4. Institute for Nanocale Technology, Sydney, Australia;5. Plasma Nanoscience Laboratories, CSIRO Manufacturing Flagship, PO Box 218, Lindfield, NSW 2070, Australia;6. Institute for Future Environments and School of Chemistry, Physics, and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4000, Australia;1. Department of Physics, Semnan University, Semnan 35195-363, Iran;2. Department of Physics, Faculty of Science, Qom University of Technology, Qom, Iran;1. Department of Physics and Jiujiang Research Institute, Xiamen University, Xiamen 361005, People''s Republic of China;2. College of Information Science and Engineering, Fujian University of Technology, Fuzhou 350118, People''s Republic of China |
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| Abstract: | Density-of-states (DOS) investigations of polytype superlattices (SLs), whose period consists of more than two different layers, are presented. Local DOS (LDOS) is computed as a function of both the electron energy and the space coordinate, which illustrates — in a direct way — the spatial localization, over the SL period, of states forming the energy minibands. A few examples of AlGaAs-based polytype SLs with a coupled-well, step-well and δ-doped basis are analysed, indicating that various LDOS distributions within SL minibands can be arranged. By changing the basis geometry, the electronic DOS can either be selectively confined to a particular SL layer or extend over the whole SL period, which provides a means of modifying the spatial overlap of states from different SL minibands and thus, tuning the respective interband transitions. In particular, polytype SLs with similar miniband structures may exhibit essentially different LDOS features and, consequently, the different transport and optical characteristics. Therefore, it is emphasized that — for a particular device application of a complex-basis SL — not only the electronic level structure should be appropriately designed, but also the corresponding space-charge distributions should be carefully considered. |
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| Keywords: | Semi-empirical models and model calculations Semiconductor-semiconductor heterostructures Superlattices |
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