Europhys. Lett.
Volume 74, Number 5, June 2006
Page(s) 875 - 881
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 03 May 2006
Europhys. Lett., 74 (5), pp. 875-881 (2006)
DOI: 10.1209/epl/i2006-10035-7

New type of Fano resonant tunneling via Anderson impurities in superlattice

S. J. Xu1, S.-J. Xiong1, 2, J. Liu3 and H. Z. Zheng3

1  Department of Physics and HKU-CAS Joint Laboratory on New Materials The University of Hong Kong - Pokfulam Road, Hong Kong, PRC
2  National Laboratory of Solid State Microstructures and Department of Physics Nanjing University - Nanjing 210093, PRC
3  State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences - Beijing 100083, PRC

received 28 February 2006; accepted in final form 5 April 2006
published online 3 May 2006

The spectrum of differential tunneling conductance in Si-doped GaAs/AlAs superlattice is measured at low electric fields. The conductance spectra feature a zero-bias peak and a low-bias dip at low temperatures. By taking into account the quantum interference between tunneling paths via superlattice miniband and via Coulomb blockade levels of impurities, we theoretically show that such a peak-dip structure is attributed to a Fano resonance where the peak always appears at the zero bias and the line shape is essentially described by a new function $\frac{\vert\tilde{\varepsilon}\vert}{\vert\tilde{\varepsilon}\vert+1}$ with the asymmetry parameter $q\approx0$. As the temperature increases, the peak-dip structure fades out due to thermal fluctuations. Good agreement between experiment and theory enables us to distinguish the zero-bias resonance from the usual Kondo resonance.

72.10.Fk - Scattering by point defects, dislocations, surfaces, and other imperfections (including Kondo effect).
73.21.Cd - Superlattices.
73.23.Hk - Coulomb blockade; single-electron tunneling.

© EDP Sciences 2006