Dresden 2003 – scientific programme

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HL: Halbleiterphysik

HL 49: Poster II

HL 49.33: Poster

Thursday, March 27, 2003, 16:30–19:00, HSZ/P2

Tunneling through self-organized quantum dot stacks — •H. Sprekeler, G. Kießlich, A. Wacker, and E. Schöll — Institut für Theoretische Physik,Technische Universität Berlin,Hardenbergstr.36, 10623 Berlin

Recently, Bryllert et al. reported on tunneling experiments through single stacks of self-assembled quantum dots[1]. Their measurements reveal sharp peaks in the current-voltage characteristics, whose width is almost independent of temperature. We report on a theoretical investigation of the tunneling processes in such a device using a Green function approach. A two-dimensional numerical simulation assuming the quantum dots to be two-dimensional pyramids is compared to a reduced model regarding the stack as a biatomic molecule. The latter case can be solved analytically. The results of the calculations are in good agreement, proposing the formation of molecular orbits within the stack for certain bias ranges. We show that in this picture the current is dominated by transmission through molecular states. The width of the current peak can thus be associated with the bias range, in which these states exist. Furthermore we present calculations, which indicate that the formation of these states underlies selection rules, which limit the possible combinations of single dot levels.
[1] T. Bryllert, M. Borgstrom, T. Sass, B. Gustafson, L. Landin, L.-E. Wernersson, W. Seifert, and L. Samuelson, Appl.Phys.Lett. 80,2681(2002).