Optics with ballistic electrons: anti-reflection coatings for GaAs/AlGaAs superlattices

The principle of anti-reflection coatings is applied to ballistic electron transport in semiconductor superlattices by adding one barrier/well pair at both sides of the superlattice. Our experiments show an increase of the transmission through the first superlattice miniband due to the anti-reflection coating by a factor of 2.4. The influence of an electric field across the superlattice on the transport in the first and second miniband is studied. Evidence for transport through individual transmission resonances in the second miniband is obtained.