Hole mixing and strain effects in the conduction intersubband transitions of undoped quantum wells

• Published in: IEEE journal of quantum electronics Vol. 40; no. 4; pp. 343 - 348
• Main Authors: Sadeghi, S.M., Wei Li
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.04.2004; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Capacitive sensors; Charge carrier processes; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Excitons; Laser transitions; Nonlinear optical devices; Nonlinear optics; Optical mixing; Optical modulation; Physics; Quantum wells; Semiconductor lasers; Ultrafast optics; Conduction bands; Quantum numbers; Quantum wells; Theoretical study; Subband; Coulomb interaction; Spinors; Electronic structure; Excitons; Dipole moments; Electronic transition; Nonlinear optics; Photoexcitation
• ISSN: 0018-9197; 1558-1713
• DOI: 10.1109/JQE.2004.824694

We study the effects of hole dispersion and mixing in the conduction intersubband transitions and infrared dressing of undoped quantum wells (QWs). This is done considering transitions of photo-excited electrons from one conduction subband (e1) to another (e2) in the presence of Coulomb interaction with the photo-excited holes. We show that, when the dispersion of the hole subband hh1 (lh1) is mainly parabolic, these transitions occur mainly between the s-states of e1-hh1 (e1-lh1) and e2-hh1 (e2-lh1) excitons with the same principal quantum numbers (allowed transitions). When the hole subbands have nonparabolic dispersions, however, such transitions are suppressed while another type of intersubband transitions in which the initial and final exciton states have different principal quantum numbers (nonallowed transitions) are enhanced. We show the enhancement and suppression processes reach their maxima when hh1 and lh1 are about to cross over, allowing multilevel mixing of excitons to occur when the undoped QW interacts with a single intense infrared field polarized along its growth. We associate these results with spinor mixing of hh1 and lh1 and illustrate how via changing the spinor contributions in these subbands one can employ strain to manipulate the dipole moments of the intersubband transitions.