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We report the observation of an electron gas in a SiGe/Si/SiGe quantum well with maximum mobility up to 240 m^2/Vs, which is noticeably higher than previously reported results in silicon-based structures. Using SiO, rather than Al_2O_3, as an insulator, we obtain strongly reduced threshold voltages close to zero. In addition to the predominantly small-angle scattering well known in the high-mobility heterostructures, the observed linear temperature dependence of the conductivity reveals the presence of a short-range random potential.
We investigate the peculiarities of the overshoot phenomena in the transverse Hall resistance R_{xy} in Si/SiGe. Near the low magnetic field end of the quantum Hall effect plateaus, when the filling factor u approaches an integer i, R_{xy} overshoot
Interactions between electrons can strongly affect the shape and functionality of multi-electron quantum dots. The resulting charge distributions can be localized, as in the case of Wigner molecules, with consequences for the energy spectrum and tunn
We report a magnetotransport study of an ultra-high mobility ($bar{mu}approx 25times 10^6$,cm$^2$,V$^{-1}$,s$^{-1}$) $n$-type GaAs quantum well up to 33 T. A strong linear magnetoresistance (LMR) of the order of 10$^5$ % is observed in a wide tempera
Metal-oxide-semiconductor field-effect transistors (MOSFETs) using atomic-layer-deposited (ALD) Al$_2$O$_3$ as the gate dielectric are fabricated on the Si/Si$_{1-x}$Ge$_x$ heterostructures. The low-temperature carrier density of a two-dimensional el
We demonstrate double quantum dots fabricated in undoped Si/SiGe heterostructures relying on a double top-gated design. Charge sensing shows that we can reliably deplete these devices to zero charge occupancy. Measurements and simulations confirm tha