Wafer-scale low-disorder 2DEG in ${}^{28}$Si/SiGe without an epitaxial Si cap

Abstract

We grow ${}^{28}$Si/SiGe heterostructures by reduced-pressure chemical vapor deposition and terminate the stack without an epitaxial Si cap but with an amorphous Si-rich layer obtained by exposing the SiGe barrier to dichlorosilane at 500 °C. As a result, ${}^{28}$Si/SiGe heterostructure field-effect transistors feature a sharp semiconductor/dielectric interface and support a two-dimensional electron gas with enhanced and more uniform transport properties across a 100 mm wafer. At T = 1.7 K we measure a high mean mobility of (1.8$\pm$0.5)$\times$10${}^5$ cm${}^2$/Vs and a low mean percolation density of (9$\pm$1)$\times$10${}^{10}$ cm${}^{-2}$. From the analysis of Shubnikov-de Haas oscillations at T = 190 mK we obtain a long mean single particle relaxation time of (8.1$\pm$0.5) ps, corresponding to a mean quantum mobility and quantum level broadening of (7.5$\pm$0.6)$\times$10${}^4$ cm${}^2$/Vs and (40$\pm$3) $\mu$eV, respectively, and a small mean Dingle ratio of (2.3$\pm$0.2), indicating reduced scattering from long range impurities and a low-disorder environment for hosting high-performance spin-qubits.

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Cited by in corpus (11)

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• Parity-conserving Cooper-pair transport and ideal superconducting diode in planar Germanium
• Low disorder and high valley splitting in silicon
• Electrical control of uniformity in quantum dot devices
• Impact of interface traps on charge noise, mobility and percolation density in Ge/SiGe heterostructures
• Single-electron occupation in quantum dot arrays at selectable plunger gate voltage
• Thin films as practical quantum materials: a status quo and beyond
• Passive and active suppression of transduced noise in silicon spin qubits
• Impact of surface treatments on the transport properties of germanium 2DHGs
• Control of threshold voltages in Si/SiGe quantum devices via optical illumination
• Highly Tunable Two-Qubit Interactions in Si/SiGe Quantum Dots by Interchanging the Roles of Qubit-Defining Gates