Carrier transport and confinement in polarization-induced three-dimensional electron slabs: Importance of alloy scattering in AlGaN

By exploiting the difference in spontaneous and piezoelectric polarization between GaN and compositionally graded layers of strained AlGaN, we demonstrate three-dimensional electron slabs of tunable widths (30–100 nm) and densities (1–5×1018cm3). Removal of ionized impurity scattering results in relatively high mobilities limited by alloy scattering at low temperatures, and by a combination of alloy and polar optical phonon scattering at room temperature. Owing to the tunable electron-electron interactions in such slabs, they offer an ideal system to probe high-field transport physics in the III-V nitride semiconductors in general, and the hot-phonon effect in particular.