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

Shubnikov–de-Haas oscillation is observed in a polarization-doped three-dimensional electron slab in a graded ${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{N}$ 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 $({\tau }_q=0.3\mathrm{}\mathrm{ps})$ is close to the transport scattering time $({\tau }_t=0.34\mathrm{}\mathrm{ps}),$ 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 $V_0=1.8\mathrm{}\mathrm{eV}$ for the ${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{N}$ 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.