An insert for a helium cryostat for experiments with a tip near the surface of a sample in superfluid helium

The design of an insert for an optical helium cryostat intended for experiments with a tip near the surface of a sample in superfluid helium is described. A piezoelectric drive used in the design is based on a bimorphous piezoceramic plate for precisely bringing a standard probe of a tunneling microscope to a sample and “softly” touching its surface with the probe tip. The insert was used in an experiment with a GaAs-AlGaAs semiconductor heterostructure with a pair of tunneling-coupled quantum wells. The possibility is demonstrated of creating a lateral potential trap in the plane of quantum wells for quasi-two-dimensional indirect excitons owing to a nonuniform distribution of the electric field in the sample near the tip.