Far-infrared magnetooptical transitions in type-III superlattices
Abstract
Far-infrared magnetooptical measurements are performed on type-III superlattices (SL's). The superlattice ${\rm \vec k\cdot\vec p}$ theory is used to analyze the experimental results. A weak magnetooptical transition, which is identified as the transitions induced by the inversion-asymmetry of the constituents, is observed in a n-type HgTe/CdTe SL. It is the first time that the effects of the inversion-asymmetry of the constituents have been observed experimentally in the SL's which they form. Inter-valence-subband magnetooptical transitions have been observed for the first time in HgTe/CdTe SL's. Theoretical analysis of the experimental results reveals that the value of the valence band offset between the bulk HgTe and CdTe could be determined more accurately by measuring these intervalence-subband transitions. The value of the offset obtained is 63 $\pm$ 13 meV. Magnetooptical transitions are observed in a novel HgTe/Hg$\sb{0.90}$Mn$\sb{0.10}$Te SL, both in the Faraday geometry and in the Voigt geometry. The magnetooptical spectra are strongly temperature sensitive. A model to calculate the electronic states in the SL's in the Voigt geometry is proposed. Magnetooptical measurements are performed on a Hg$\sb{0.96}$Mn$\sb{0.04}$Te/CdTe SL. The theoretical results fit the experimental ones well. The effects of electric field on the electronic states localized in a CdTe/HgTe/CdTe quantum well are investigated theoretically. The results show that strong electrooptical effects exist in the quantum well, which suggests that such quantum well structures may be a good candidate for electrooptical devices with working wavelengths from 3 to 13 $\mu$m. The effective masses, both parallel and normal to the interfaces, of the electrons on the first conduction subband in HgTe/CdTe SL's are studied theoretically. The results show that far-infrared magnetooptical transitions in the Voigt geometry could be observed in HgTe/CdTe SL's under certain conditions.
Degree
Ph.D.
Advisors
Furdyna, Purdue University.
Subject Area
Condensation
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.