Magnetotransport properties of a polarization-doped three-dimensional electron slab in graded AlGaN

Shubnikov\char21{}de-Haas oscillation is observed in a polarization-doped three-dimensional electron slab in a graded ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{N}$ semiconductor layer. The electron slab is generated by the technique of grading the polar semiconductor alloy with spatially changing polarization. Temperature-dependent oscillations allow us to extract an effective mass of ${m}^{*}{=0.21m}_{0}.$ The quantum scattering time measured $({\ensuremath{\tau}}_{q}=0.3\mathrm{ps})$ is close to the transport scattering time $({\ensuremath{\tau}}_{t}=0.34\mathrm{ps}),$ indicating the dominance of short-range scattering. Alloy scattering is determined to be the dominant mechanism-limiting mobility; this enables us to extract an alloy-scattering parameter of ${V}_{0}=1.8\mathrm{eV}$ for the ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{N}$ material system. Polarization-doping presents an exciting technique for creating electron slabs with widely tunable density and confinement for the study of dimensionality effects on charge transport and collective phenomena.