  Nanostructures in InAs quantum wells have so far remained outside of the
scope of traditional microfabrication techniques based on etching. This is due
to parasitic parallel conduction arising from charge carrier accumulation at
the physical edges of samples. Here we present a technique which enables the
realization of quantum point contacts and quantum dots in two-dimensional
electron gases of InAs purely by electrostatic gating. Multiple layers of top
gates separated by dielectric layers are employed. Full quantum point contact
pinch-off and measurements of Coulomb-blockade diamonds of quantum dots are
demonstrated.
