Imaging of a suspended helium film with 2-D electrons by interferometry

A helium film suspended between elevations on a substrate forms an excellent surface for a two-dimensional electron gas. With the structure on the substrate a quasi one-dimensional electron system can be created. Experiments probing the electrical transport properties of this system have raised questions about the suspended helium film itself. We report measurements of the suspended film using interferometry. The profile is mapped out as a function of the bull helium level beneath the substrate. By measuring the electron signal simultaneously the relation between the signal and the film profile can be obtained.