Charge Transport Laboratory @ Northwestern University
Used for: | Low Temperature Lab |
FUNCTION:
The Charge Transport Laboratory includes equipment to perform variable temperature DC electrical conductivity and Hall measurements (mobility and carrier concentration), from 4.2 K to 340 K using a computer automated four- and five-probe technique, respectively.
Typical samples can range from thin films to single crystals, with specimens mounted on interchangeable sample holders. Hall measurements are made with a magnetic flux density of 0.74 Tesla. The measurements of the sample cross-sectional area and voltage probe separations (Hall and conductivity) are made with a calibrated Bausch & Lomb binocular microscope.
EQUIPMENT:
DC electrical conductivity and Hall measurements: Liquid helium/liquid nitrogen cryostat and associated equipment (such as vacuum pumps), and lab-made dipsticks for sample mounting. Keithley and Lake Shore rack-mounted source-measure and switching equipment are all GPIB controlled by a computer running control software written using LabView. A Lake Shore electromagnet and power supply are used for the Hall measurements. Sample preparation includes various fine tweezers and wire, conductive dags, colloids, pastes, etc.. A calibrated Bausch & Lomb binocular microscope is used to mount and physically characterize the specimens under test.