MBE Growth and Characterization of Hg Based Compounds and Heterostructures
WUERZBURG UNIV (GERMANY F R) PHYSIKALISCHES INST
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The molecular beam epitaxy MBE growth of Mercury Cadmium Telluride Hg1-xCdxTe alloys and type III HgTeHg1-xCdxTe heterostructures has been discussed, including similarities and differences between the 0 0 1 and 1 1 2Beta orientations. Furthermore, the MBE growth of HgTe-based quantum wells QWs with the incorporation of Mn are additional topics. An investigation of the optical properties of type III superlattices with a normal band structure has lead to information about band structure of these heterostructures as well as information about the interface and the semimetallic QW. For example, by means of the full 8 x 8 Kane Hamiltonian in the envelope function approximation, it has been demonstrated that the energy separation between the H1-E1 and L1-E1 intersubband transition energies is primarily determined by the valence band offset, Lambda, between HgTe and CdTe. This has led to unambiguous values for the offset and its temperature dependence i.e., LambdaTau 570 plus or minus 60 meV and dLambdadTau -0.40 plus or minus 0.04Tau meVK. Furthermore, the energy gap of HgTe at room temperature also has been determined. Magneto-transport measurements of n-type QWs show very pronounced Shubnikov-de Haas SdH oscillations and well-developed quantum Hall plateaus for temperatures up to approximately 60 K. A large Rashba spin-orbit splitting of the first conduction subband, H1, has been observed in HgTeHg1-xCdxTe QWs with an inverted band structure. Self-consistent Hartree calculations of the band structure based on the above model allows the authors to quantitatively describe the experimental results and demonstrates that the heavy hole nature of the H1 subband greatly influences the spatial distribution of electrons in the QW, thus enhancing the Rashba spin splitting. 9 figures, 41 refs.
- Solid State Physics