ISSN 1063-7761, Journal of Experimental and Theoretical Physics, 2011, Vol. 113, No. 4, pp. 692–697. © Pleiades Publishing, Inc., 2011. 692 1 1. INTRODUCTION A large class of materials of great importance for quantum electronics, such as the arrays of metallic [1, 2] or semiconducting [3] quantum dots (QDs), consist of weakly coupled nanometer-scale islands. Various physical effects have been investigated in large peri- odic arrays of QDs [4]. The study of aperiodic sequences of QDs began quite recently [5]. In aperi- odic structures, a small perturbation does not localize electrons, and transport is available at finite values of perturbations (external fields), in contrast to periodic one-dimensional structures, where even an infinitesi- mal perturbation localizes the current states [6]. In this paper, we study the electronic spectra and electronic transport properties in one-dimensional aperiodic sequences of QDs of the Thue–Morse and double-periodic type [7]. Two ways to construct the aperiodic sequences are considered: by defining the confining potential steepness and by defining the dis- tances between QDs. Aperiodic sequences of QDs based on GaAs and its solid solution Al x Ga 1– x As and In x Ga 1– x As with x = 0.1–1 are considered. In the quasiclassical approximation, we obtain the tunneling probability for double QDs and aperiodic sequences of QDs and investigate the influence of control parame- ters such as external fields and the confining potential steepness on the electronic transport and electronic spectra. The resonance tunneling states appear when energy levels of neighboring QDs become equal as a result of shifting electronic energy levels by the exter- nal fields. 1 The article is published in the original. 2. THE THUE–MORSE AND DOUBLE- PERIODIC APERIODIC SEQUENCES The Thue–Morse sequence can be defined by the recursive relations S n = S n –1 and = (for n ≥ 1) with S 0 = A and = B. Another way to build this sequence is through the inflation rules A AB and B BA. Generations of the Thue–Morse sequence are The double-periodic sequence is invariant under the transformation B AA. Generations of the dou- ble-periodic sequence are We use the two ways to build each aperiodic struc- ture under investigation. (1) By defining the confining potential steepness. This means that A is a QD with the parabolic confining potential steepness α 1 and B is a QD with the parabolic confining potential steepness α 2 . The distances between the QDs are equal. (2) By defining the distance between the QDs. This means that A is a pair of QDs with a separation d A and B is a pair of QDs with a separation distance d B . The confining potential steepnesses are the same for all QDs. S n 1 – + S n + S n 1 – + S n 1 – S 0 + S 0 A , S 1 AB , S 2 ABBA , = = = S 3 ABBABAAB . = S 0 A , S 1 AB , S 2 ABAA , = = = S 3 ABAAABAB . = Electronic Excitations and Transport in Aperiodic Sequences of Quantum Dots in External Electric and Magnetic Fields 1 P. Yu. Korotaev a , N. E. Kaputkina a , Yu. E. Lozovik b , and Yu. Kh. Vekilov a a National University of Science and Technology “MISIS”, Moscow, 119049 Russia b Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow Region, 142190 Russia e-mail: pvl.korotaev@gmail.com Received December 3, 2010 Abstract—The energy spectra and transport of electronic excitations in one-dimensional aperiodic sequences of quantum dots of Thue–Morse and double-periodic type are studied. The influence of external magnetic and electric fields on the energy spectra and transport is considered. For aperiodic sequences of quantum dots, in contrast to aperiodic sequences of atoms, the influence of relatively small magnetic and electric fields is essential, but localization occurs at finite values of the perturbations. The transmission coef- ficient is determined using the quasiclassical approximation with the Coulomb blockade taken into account. The resonance tunneling is studied. DOI: 10.1134/S1063776111100049 ELECTRONIC PROPERTIES OF SOLID