Characterization of BEEM Performance

Kathleen McCreary

Previous work done at Wooster, completed by Austin Carter in 2005, focused on converting the scanning tunneling microscope (STM) to a ballistic electron emission microscope (BEEM). The performance of the BEEM was analyzed using a Au/GaAs sample obtained from Dr. Jon Pelz at Ohio State University. When functioning properly, the measured collector current for the Au/GaAs sample should be in the range of a few hundred pico amps. For the majority of data recorded, the collector currents were a few nano-amps or larger. The only data which displayed collector currents in the expected range were those in which the BEEM probe had been set down very hard on the top gold contact. This leads us to believe that poor electrical contact is the main contributor to the high collector current. To consistently achieve good electrical contact between the BEEM probe and the top gold layer, the experimental setup will need to be altered in the future.