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Activated and metallic conduction in p -type modulation-doped Ge - Sn devices
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Gul, Y., Myronov, Maksym, Holmes, S. N. and Pepper, M. (2020) Activated and metallic conduction in p -type modulation-doped Ge - Sn devices. Physical Review Applied, 14 (5). 054064. doi:10.1103/physrevapplied.14.054064
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Official URL: https://doi.org/10.1103/PhysRevApplied.14.054064
Abstract
Ge1−xSnx quantum wells can be incorporated into Si−Ge–based structures with low-carrier effective masses, high mobilities, and the possibility of direct band-gap devices with x ∼ 0.1. However, the electrical properties of p-type Ge1−xSnx devices are dominated by a thermally activated mobility and metallic behavior. At 30 mK the transport measurements indicate localization with a mobility of
380cm2/Vs, which is thermally activated with a temperature-independent carrier density of 4 × 1011cm−2. This weakly disordered system with conductivity, σ ∼ e2/h, where e is the fundamental charge and h is Planck’s constant, is a result of negatively charged “Sn-vacancy” complex states in the barrier layers that act as hole traps. A measured hole effective mass of 0.090 ± 0.005me from the Shubnikov-de Haas effect, where me is the free electron mass shows that the valence band is heavy hole dominated and is similar to p-type
Ge with the compressive strain playing the role of quenching the spin-orbit coupling and shifting the unoccupied light-hole states to higher hole energies. The Ge1−xSnx devices have a high quantum mobility of approximately 36 000 cm2/Vs that is not thermally activated. The ratio of transport-to-quantum mobility of approximately 0.01 in
Ge1−xSnx devices is unusual and points to several competing scattering mechanisms in the different experimental regimes.
| Item Type: | Journal Article | ||||||
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| Subjects: | Q Science > QC Physics T Technology > TK Electrical engineering. Electronics Nuclear engineering |
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| Divisions: | Faculty of Science > Physics | ||||||
| SWORD Depositor: | Library Publications Router | ||||||
| Library of Congress Subject Headings (LCSH): | Quantum scattering , Metal oxide semiconductor field-effect transistors , Germanium | ||||||
| Journal or Publication Title: | Physical Review Applied | ||||||
| Publisher: | American Physical Society (APS) | ||||||
| ISSN: | 2331-7019 | ||||||
| Official Date: | 24 November 2020 | ||||||
| Dates: |
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| Date of first compliant deposit: | 12 January 2021 | ||||||
| Volume: | 14 | ||||||
| Number: | 5 | ||||||
| Article Number: | 054064 | ||||||
| DOI: | 10.1103/physrevapplied.14.054064 | ||||||
| Status: | Peer Reviewed | ||||||
| Publication Status: | Published | ||||||
| Access rights to Published version: | Restricted or Subscription Access | ||||||
| Copyright Holders: | © 2020 American Physical Society | ||||||
| RIOXX Funder/Project Grant: |
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