Ultra high hole mobilities in a pure strained Ge quantum well

Mironov, O. A.; Hassan, A. H. A.; Morris, R. J. H.; Dobbie, A.; Uhlarz, M.; Chrastina, D.; Hague, J. P.; Kiatgamolchai, Somchai; Beanland, Richard; Gabáni, S.; Berkutov, I. B.; Helm, M.; Drachenko, O.; Myronov, Maksym; Leadley, D. R.

doi:10.1016/j.tsf.2013.10.118

Cited by 14 publications

(12 citation statements)

References 25 publications

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“…In contrast, Ge-rich strained Si/Ge heterostructures are also highly attractive for various applications such as high-mobility channels for metal-oxide-semiconductor field-effect transistors (MOSFETs) and photonic devices. [2][3][4][5][6][7][8][9] It is generally difficult, however, to grow highquality Ge-rich SiGe alloys on Si due to the large lattice mismatch. By replacing the Si substrate with Ge, it can be easier to grow high-quality Ge-rich SiGe, but the fact that the bulk Ge wafer is still costly and not appropriate for mass production has prevented intensive research so far.…”

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confidence: 99%

A drastic increase in critical thickness for strained SiGe by growth on mesa-patterned Ge-on-Si

Wagatsuma

Alam

Okada

et al. 2021

Appl. Phys. Express

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We demonstrate that the critical thickness for Ge-rich strained SiGe layers can be drastically increased by a factor of more then two by means of growth on mesa-patterned Ge-on-Si. The Si0.2Ge0.8 layer grown on sub-millimeter mesa Ge-on-Si is fully strained and free from ridge roughness, while the same Si0.2Ge0.8 layers grown on unpatterned Ge-on-Si and a Ge substrate are partially strain-relaxed with the surface covered by high-density ridge roughness. This demonstrates that the proposed patterning method can provide thick and stable strained SiGe films as promising templates for realization of strained SiGe-based optoelectronic and spintronic devices.

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confidence: 99%

A drastic increase in critical thickness for strained SiGe by growth on mesa-patterned Ge-on-Si

Wagatsuma

Alam

Okada

et al. 2021

Appl. Phys. Express

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“…[11][12][13] In addition, hole transport in Ge has the added advantage that hole wavefunctions vanish at the nucleus, further suppressing the hyperfine interaction. 14 For the production of high-quality high-electron mobility transistors (HEMTs) and non-local spin injection and detection devices, SiGe heterostructures are also expected to offer advantages over bulk Si and Ge epilayers, owing to increased mobility 12,15,16 and quantum confinement effects. 2 Ideally, spintronic devices would use SiGe heterostructures containing p-Ge quantum wells to fully utilise all of these advantages.…”

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confidence: 99%

Magnetotransport in p-type Ge quantum well narrow wire arrays

Newton

Llandro

Mansell

et al. 2015

Applied Physics Letters

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We report magnetotransport measurements of a SiGe heterostructure containing a 20 nm p-Ge quantum well with a mobility of 800 000 cm2 V−1 s−1. By dry etching arrays of wires with widths between 1.0 μm and 3.0 μm, we were able to measure the lateral depletion thickness, built-in potential, and the phase coherence length of the quantum well. Fourier analysis does not show any Rashba related spin-splitting despite clearly defined Shubnikov-de Haas oscillations being observed up to a filling factor of ν = 22. Exchange-enhanced spin-splitting is observed for filling factors below ν = 9. An analysis of boundary scattering effects indicates lateral depletion of the hole gas by 0.5 ± 0.1 μm from the etched germanium surface. The built-in potential is found to be 0.25 ± 0.04 V, presenting an energy barrier for lateral transport greater than the hole confinement energy. A large phase coherence length of 3.5 ± 0.5 μm is obtained in these wires at 1.7 K.

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“…The high quality growth process has been outlined in a series of publications over the last few years. 14,16 Polyimide was used as a gate dielectric with a nominal thickness of 430 nm after annealing at 300 C for 60 min. Typical channel depletion voltages were $þ2 V. Hall bar mesas were prepared using optical lithography with S1813 resist and dry etched with a CF 4 plasma.…”

Section: A Growth and Processingmentioning

confidence: 99%

Spin-splitting in p-type Ge devices

Holmes

Newton

Llandro

et al. 2016

Journal of Applied Physics

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Compressively strained Ge quantum well devices have a spin-splitting in applied magnetic field that is entirely consistent with a Zeeman effect in the heavy hole valence band. The spin orientation is determined by the biaxial strain in the quantum well with the relaxed SiGe buffer layers and is quantized in the growth direction perpendicular to the conducting channel. The measured spinsplitting in the resistivity q xx agrees with the predictions of the Zeeman Hamiltonian where the Shubnikov-deHaas effect exhibits a loss of even filling factor minima in the resistivity q xx with hole depletion from a gate field, increasing disorder or increasing temperature. There is no measurable Rashba spin-orbit coupling irrespective of the structural inversion asymmetry of the confining potential in low p-doped or undoped Ge quantum wells from a density of 6 Â 10 10 cm À2 in depletion mode to 1.7 Â 10 11 cm À2 in enhancement. Published by AIP Publishing.

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Ultra high hole mobilities in a pure strained Ge quantum well

Cited by 14 publications

References 25 publications

A drastic increase in critical thickness for strained SiGe by growth on mesa-patterned Ge-on-Si

A drastic increase in critical thickness for strained SiGe by growth on mesa-patterned Ge-on-Si

Magnetotransport in p-type Ge quantum well narrow wire arrays

Spin-splitting in p-type Ge devices

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