Theory of the channel-width dependence of the low-temperature hole mobility in Ge-rich narrow square<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>Si</mml:mi><mml:mo>∕</mml:mo><mml:mi>SiGe</mml:mi><mml:mo>∕</mml:mo><mml:mi>Si</mml:mi></mml:mrow></mml:math>quantum wells

This paper describes a complete analytical formalism for calculating electron subband energy and degeneracy in strained multi-valley quantum wells grown along any orientation with explicit results for AlAs quantum wells. In analogy to the spin index, the valley degree of freedom is justified as a pseudospin index due to the vanishing intervalley exchange integral. A standardized coordinate transformation matrix is defined to transform between the conventional-cubic-cell basis and the quantum well transport basis whereby effective mass tensors, valley vectors, strain matrices, anisotropic strain ratios, piezoelectric fields, and scattering vectors are all defined in their respective bases. The specific cases of (001) (411)-oriented QWs and we define and solve for a shear-to-biaxial strain ratio. The notation is generalized to address non-Miller-indexed planes so that miscut substrates can also be treated, and the treatment can be adapted to other multi-valley biaxially strained systems. To help classify anisotropic intervalley scattering, a valley scattering primitive unit cell is defined in momentum space which allows one to distinguish purely in-plane momentum scattering events from those that require an out-of-plane momentum component.

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“…Following Quang et al 65,66 the scattering potential U RS for the QW with a square potential and a well width W is given by…”

Section: The Valley Scattering Unit Cell and Anisotropic Intervmentioning

confidence: 99%

“…The standard model for alloy disorder scattering 65,67 with variable alloy composition x(z) is described by the autocorrelation function…”

Section: The Valley Scattering Unit Cell and Anisotropic Intervmentioning

confidence: 99%

Valley degeneracy in biaxially strained aluminum arsenide quantum wells

et al. 2011

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“…These strain fluctuations in turn induce nonuniform shifts of the band edges, and so act on the charge carriers as a scattering source. It should be stressed that the misfit deformation potentials for two kinds of carrier are quite different, viz., the one for electrons is fixed by a single normal diagonal component of the strain field [6], whereas the one for holes by all its components [11]. The roughness-induced misfit deformation potential for holes in a cubic crystal is…”

Section: Misfit Deformation Potentialmentioning

confidence: 99%

“…In Eq. (29) b s and d s are the shear deformation potential constants of the well layer, and its anisotropy ratio is α, elastic constants K, G are given in [11].…”

Section: Misfit Deformation Potentialmentioning

confidence: 99%

“…However, from the carrier density dependence of the mobility and the transport to quantum lifetime ratio, the others [8] assumed ionized impurity scattering to be dominant. Thirdly, in their calculations the roughness-related misfit deformation potential scattering has been ignored, which was proven to be important for Institute of Engineering Physics, HUT, 1 Dai Co Viet Road, Hanoi, Vietnam on low-temperature transport properties of the charge carriers confined in a square infinite Centre for Theoretical Physics, VAST, 10 Dao Tan Str., Hanoi, Vietnam strained Si [10] and SiGe [11] channels. Just recently, some experimental [8] and theoretical [12] studies have indicated that the doping-induced confinement may be of great importance for the QW mobility.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Single-Side Modulation Doping on Low-Temperature Transport Properties in Square Infinite Quantum Wells

Tung¹,

Quang²,

Hien³

Springer Proceedings in Physics

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Abstract.A variational approach is given for the effect from single-side modulation doping quantum well (QW). We obtained analytic expressions which describe the doping effects on the carrier distribution in the well, their roughness-induced scattering in the in-plane and screening by them. The calculation of the transport lifetimes is performed for holes in a SiGe/Ge/SiGe square QW, and the result is found in quantitative agreement with recently measured dependence on experimental conditions such as channel width and carrier density.

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