Undoped electron-hole bilayers in a GaAs∕AlGaAs double quantum well

The authors present the fabrication details of completely undoped electron-hole bilayer devices in a GaAs∕AlGaAs double quantum well heterostructure with a 30nm barrier. These devices have independently tunable densities of the two-dimensional electron gas and two-dimensional hole gas. The authors report four-terminal transport measurements of the independently contacted electron and hole layers with balanced densities from 1.2×1011cm−2 down to 4×1010cm−2 at T=300mK. The mobilities can exceed 1×106cm2V−1s−1 for electrons and 4×105cm2V−1s−1 for holes.