Light effective hole mass in undoped Ge/SiGe quantum wells
Mario Lodari (Kavli institute of nanoscience Delft, TU Delft - QuTech Advanced Research Centre, TU Delft - QCD/Scappucci Lab)
A. Tosato (TU Delft - QuTech Advanced Research Centre, TU Delft - QCD/Scappucci Lab, Kavli institute of nanoscience Delft)
Diego Sabbagh (TU Delft - QuTech Advanced Research Centre, Kavli institute of nanoscience Delft, TU Delft - QCD/Scappucci Lab)
Markus Andreas Schubert (Innovations for High Performance Microelectronics)
Giovanni Capellini (University of Roma Tre, Innovations for High Performance Microelectronics)
A. Sammak (TNO, TU Delft - Business Development)
M. Veldhorst (TU Delft - QCD/Veldhorst Lab)
Giordano Scappucci (TU Delft - QCD/Scappucci Lab, TU Delft - QuTech Advanced Research Centre, Kavli institute of nanoscience Delft)
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Abstract
We report density-dependent effective hole mass measurements in undoped germanium quantum wells. We are able to span a large range of densities (2.0-11×1011cm-2) in top-gated field effect transistors by positioning the strained buried Ge channel at different depths of 12 and 44 nm from the surface. From the thermal damping of the amplitude of Shubnikov-de Haas oscillations, we measure a light mass of 0.061me at a density of 2.2×1011cm-2. We confirm the theoretically predicted dependence of increasing mass with density and by extrapolation we find an effective mass of ∼0.05me at zero density, the lightest effective mass for a planar platform that demonstrated spin qubits in quantum dots.
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