Benefits of using undoped GaAs/AlGaAs heterostructures: A case study of the zero-bias bias anomaly in quantum wires

We use quantum wires fabricated on undoped GaAs/AlGaAs heterostructures in which the average impurity separation is greater than the device size to compare the behaviour of the zero-bias anomaly against predictions from Kondo and spin polarisation models. Cleanliness and reproducibility are significantly improved in our undoped devices when compared to our doped devices.