Imaging Electron Interferometer
Abstract
The research supported by this grant is aimed at imaging the flow of electron waves through a two dimensional electron gas (2DEG) to understand both the fundamental quantum behavior that appears in semiconductor nanostructures at low temperatures, and to study the propagation of electron waves through semiconductor structures with interesting geometries. A custom-made liquid He cooled scanning probe microscope (SPM) was developed in Westervelt's group to carry out the measurements. The conducting SPM tip acts as a moveable gate that locally depletes the electron gas below, creating a scattering center that reflects electron waves. By measuring the conductance of the devices as the SPM tip is raster scanned above, an image of electron flow is obtained. Electron flow was imaged in two types of devices: (1) An Electron Interferometer, in which electron waves traveling away from a quantum point contact (QPC) reflect both from a mirror and from the depleted disc beneath the SPM tip. (2) Magnetic Focusing device, in which electrons traveling away from a QPC flow around cyclotron orbits in a perpendicular magnetic field and leave through a second QPC pointed in the same direction - a peak in conductance is observed when the spacing between the two QPCs is an integer multiple of the cyclotron diameter.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 16, 2011
- Accession Number
- ADA544621
Entities
People
- R. M. Westervelt
Organizations
- Harvard University