Hall-effect measurement

The Hall-effect measurement is a common technique used to assess semiconductor material quality, speed, and electron density. The signal-to-noise ratio of the Hall-effect measurement improves when the magnitude of the applied magnetic field is increased. Unfortunately, this has necessitated that measurements be performed in a cryogenic vacuum chamber (i.e. a cryostat) with a large superconducting magnet, requiring special sample preparation and long queues to access the measurement setup.

For this summer project, we seek to create our own Hall-effect measurement setup that uses a small, powerful needle-sized electromagnet that can be positioned directly over the sample under test. By reducing the size of the electromagnet, we are able to position the magnetic field directly over the sample and reduce the cooling requirements necessary to produce large, 1-T magnetic fields. In the project, the student will build the electromagnetic around the tip of a needle used to electrically probe semiconductor devices. The probe will be connected to a micropositioner allowing the electromagnet to be position directly over the area of interest.