Quasibound states in graphene quantum-dot nanostructures generated by concentric potential barrier rings
Jiang Zhao-Tana,Yu Cheng-Longa,Dong Quan-Lib
a. School of Physics, Beijing Institute of Technology, Beijing 100081, China;
b. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Abstract We study the quasibound states in a graphene quantum-dot structure generated by the single-, double-, and triple-barrier electrostatic potentials. It is shown that the strongest quasibound states are mainly determined by the innermost barrier. Specifically, the positions of the quasibound states are determined by the barrier height, the number of the quasibound states is determined by the quantum-dot radius and the angular momentum, and the localization degree of the quasibound states is influenced by the width of the innermost barrier, as well as the outside barriers. Furthermore, according to the study on the double- and triple-barrier quantum dots, we find that an effective way to generate more quasibound states with even larger energy level spacings is to design a quantum dot defined by many concentric barriers with larger barrier-height differences. Last, we extend our results into the quantum dot of many barriers, which gives a complete picture about the formation of the quasibound states in the kind of graphene quantum dot created by many concentric potential barrier rings.
Received: 29 October 2011
Revised: 24 November 2011
Accepted manuscript online:
Fund: Project supported by the National Natural Science Foundation of China (Grant Nos. 10974015 and 11074297) and the Program for New Century Excellent Talents in University (Grant No. NCET-08-0044).
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