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Comment: 3 pages, 1 figure; presented at the DARPA SPinS review (#Th-19), San Francisco, CA, October 25-28, 2004
Comment: an error in earlier version corrected
Comment: RevTex file, 3 PS figures
We analyze spin splitting of the two-dimensional hole spectrum in strained asymmetric SiGe quantum wells (QWs). Based on the Luttinger Hamiltonian, we obtain expressions for the spin-splitting parameters up to the third order in the in-plane hole wavevector. The biaxial strain of SiGe QWs is found to be a key parameter that controls spin splitting. Application to SiGe field-effect transistor structures indicates that typical spin splitting at room temperature varies from a few tenth of meV in the case of Si QW channels to several meV for the Ge counterparts, and can be modified efficiently by gate-controlled variation of the perpendicular confining electric field. The analysis also shows that for sufficiently asymmetric QWs, spin relaxation is due mainly to the spin-splitting related D'yakonov-Perel' mechanism. In strained Si QWs, ou...
We have investigated spatio-temporal kinetics of electron spin polarization in semiconductor narrow 2D strip and explored the ability to manipulate spin relaxation. Information about spin of the conduction electrons and mechanisms of spin rotation is incorporated into transport Monte Carlo simulation program. A model problem, involving linear-in-k splitting of the conduction band, responsible for the D'yakonov-Perel' mechanism of spin relaxation in the zinc-blende semiconductors and heterostructures, is solved numerically to yield the decay of spin polarization of an ensemble of electrons in the 2D channel of finite width. For very wide channels, a conventional 2D value of spin relaxation is obtained. With decreasing channel width the relaxation time soares rapidly by orders of magnitude. Surprisingly, the cross-over point between 2D...
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