طیف الکترونیکی سیستم های فیبوناچی شبه منظم: تجزیه و تحلیل از مدل های ساده 1D
|کد مقاله||سال انتشار||مقاله انگلیسی||ترجمه فارسی||تعداد کلمات|
|27964||2005||4 صفحه PDF||سفارش دهید||2292 کلمه|
Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : Microelectronics Journal, Volume 36, Issue 10, October 2005, Pages 882–885
The electronic spectra of quasi-regular systems grown following the Fibonacci sequence are investigated via simple one-dimensional tight-binding, one-band models. Different models are considered and the influence of the model parameters and the number of atoms entering the different blocks on the electronic spectrum are discussed.
The quasi-regular systems have been intensively studied in the last years , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,  and . The interest was triggered from the theoretical side by the prediction that these systems should manifest non-conventional electron and phonon states , ,  and , and exhibit energy spectra with a high fragmentation and fractal character ,  and . The experimental growth of Fibonacci  and  and Thue–Morse  multilayer structures has provided the practical realization of these systems. The Fibonacci system, a linear lattice constructed recursively, is the one-dimensional (1D) version of the quasi-crystals , ,  and , and has been the subject of many theoretical studies. The electronic structure of the Fibonacci system has been investigated mainly in the single-band tight-binding limit. In these studies, it was found that the energy spectrum is self-similar, in the sense that the energy bands divide into three subbands, each of which further subdivides into three, and so on , ,  and , thus producing a singular continuous spectrum , which in the infinite limit reduces to a Cantor-like spectrum with dense energy gaps everywhere , ,  and . More realistic studies, using an empirical tight-binding (ETB) sp3s* Hamiltonian , were presented in , , , , ,  and . In these works, the Fibonacci spectrum was only estimated for certain energy ranges and for wave vectors in the vicinity of the superlattice Γ point. We delve here into the properties arising from the simple models, by considering possible variations in the basic structure of these models, as a parallel to the more sophisticated and realistic sp3s* Hamiltonians. In Section 2, a brief description of the theoretical models is given and conclusions are provided in Section 3.
نتیجه گیری انگلیسی
We studied the electronic spectrum of Fibonacci quasi-regular systems, by means of simple 1D models. We note that many 1D models are not faithful representations of the experimentally grown Fibonacci heterostructures. The main feature of the electronic spectrum for the simple 1D models is the spectrum fragmentation characterized by the presence of primary and secondary gaps. There is also a kind of qualitative self-similarity reflected in the trifurcation of the subbands, although this is not a true self-similarity as in the Cantor set. In finite systems, described by simple 1D models, the details of the spectrum depend quite significantly on the values of the model parameters.