Fano Resonances and Electron Localization
in Heterobarriers

C. S. Kim ¹, A. M. Satanin^2, *, and V. B. Shtenberg ^2, **

¹Department of Physics, Chonnam National University, Kwangju, Korea

²Nizhni Novgorod State University, NizhniNovgorod, 603600 Russia

*e-mail: satanin@phys.unn.runnet.ru

**e-mail: shten@phys.unn.runnet.ru

Received January 3, 2000

Abstract—A study is made of electron tunneling in semiconductor heterostructures having a complex disper-
sion law. A generalized Fabry–Perot approach is used to describe tunneling across the barrier. Mixing of elec-
tron states at the heterojunctions is responsible for the asymmetric resonant structure of the transmission which
is characterized by a resonance–antiresonance pair. The resonance corresponds to a pole while the antireso-
nance corresponds to a zero of the scattering amplitude in the complex energy plane, i.e., near the pole and the
zero the transmission of the heterobarrier has a Fano resonance structure. It is shown that for certain barrier
parameters the resonances may collapse and localized states may appear in the heterobarrier, which is observed
on the current–voltage characteristics of the barriers. The two-valley model of a GaAs/Al_xGa_{1 – x} As/GaAs het-
erostructure is considered as an example. An analysis is made of the resonance structure in the barrier as a func-
tion of the type of boundary conditions used for the heterojunctions. The low-temperature current–voltage char-
acteristic of the barrier is calculated. © 2000 MAIK “Nauka/Interperiodica”.

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