Metal–insulator-transition studied by single-electron tunneling

We present measurements of single-electron tunneling in a vertical GaAs/AlGaAs double-barrier resonant-tunneling device with a low emitter doping. The transport spectrum of our sample exhibits a series of differential conductance peaks which experience an exponential shift to higher voltages with magnetic fields beyond a critical magnetic field. We attribute this effect to a metal-insulator transition in our device. A detailed analysis of the temperature-dependence of this effect is shown.