Electric-Field Effects on the Band-Edge States of GaAs/AlAs Coupled Quantum Wells

Abstract

PACS: 73.21.FgOptical experiments on electric field tunable AlAs/GaAs coupled quantum wells demonstrate that the optical nature of these structures can be directly controlled by an applied electric field. In this work we are concerned with calculation and analysis of the first electron and hole states in these structures. We take into account the effects of the heterostrucuture geometry and of the external uniform electric field applied perpendicularly to the layers, which may lead to an anticrossing of low-lying electron levels in the system. Calculations are performed within the tight-binding supercell formalism with interactions between atomic orbitals up to second nearest neighbors. Our results show that for GaAs layers less than %30 A wide, the application of electric fields turns the heterostructures from type II to type I behavior. Our estimated value of the electric field intensity needed to realize this transition is in good agreement with the experimental results for comparable heterostructure geometry.

Electric-field-induced Nonlinear Optical Rectification, Second- and Third-harmonic Generation in Asymmetrical Quantum Well

“…However, to the best of our knowledge, effects of a static electric field on the optical harmonic generations in this system have not been investigated so far. Optical experiments on electric field-tunable quantum wells make manifest the electric field-controllability of the optical response of these structures [32]. An applied electric field modifies the potential energy profile of the structure and accordingly alters the subband energy levels [33].…”