Optical absorption of polarized light in InAs/GaSb quantum wells

• Published in: Semiconductor science and technology Vol. 23; no. 12; p. 125044
• Main Authors: Zakharova, A, Semenikhin, I, Chao, K A
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.12.2008
• Subjects: Condensed Matter Physics; Den kondenserade materiens fysik; Fysik; Natural Sciences; Naturvetenskap; Physical Sciences; TECHNOLOGY; TEKNIKVETENSKAP
• ISSN: 0268-1242; 1361-6641; 1361-6641
• DOI: 10.1088/0268-1242/23/12/125044

Using an eight-band k p model Hamiltonian with the Burt-Foreman envelope function theory, we have investigated the optical absorption of both linearly and circularly polarized light, as well as related phenomena in InAs/GaSb broken-gap quantum wells grown along the [0 0 1] direction, with emphasis on the effects of electron-hole hybridization and the various symmetry-breaking mechanisms such as structural inversion asymmetry, bulk inversion asymmetry and interface Hamiltonian. The optical matrix elements exhibit unusual angular dependence in close connection with the spin-flip transitions which are originally forbidden. The spin split of the 2e subband results in two profound absorption peaks for the 1hh-2e transition for both linearly polarized and circularly polarized light. A large lateral optical anisotropy appears in the absorption coefficient of linearly polarized light, which can reach almost 100% with a reducing thickness of the quantum well. For the absorption of circularly polarized light, we found a large enhancement of electron spin polarization in the upper 2e subband, which was generally considered as forbidden if the polarization is along the direction perpendicular to the plane-of-light incidence. © 2008 IOP Publishing Ltd.