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 30 nm 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 1.2x10(11) cm(-2) down to 4x10(10) cm(-2) at T=300 mK. The mobilities can exceed 1x10(6) cm(2) V-1 s(-1) for electrons and 4x10(5) cm(2) V-1 s(-1) for holes.