Passivation of donors in electron beam lithographically defined nanostructures after methane/hydrogen reactive ion etching

We show that while the methane/hydrogen gas mixture is capable of etching GaAs and AlGaAs controllably and with little residual damange, it leads to the passivation of donors in both semiconductors. The passivation can, however, be annealed out with a short thermal cycle to 300 °C. The effects of passivation are illustrated and characterized by processing uniform epilayers and quantum wires in n+-GaAs and modulation doped AlGaAs/GaAs heterostructures.