Hall Effect




Fabricate two semiconductor Hall samples (one p-type and one n-type) and one copper sample.  On each sample, measure resistivity and Hall voltages by following the instructions in the NIST manual and filling out the handy worksheet from the NIST manual.  You may want to perform the sequence of Hall voltage measurements for different values of current and magnetic field.



Fabrication of semiconductor samples:


Making a good metal-semiconductor contact is not trivial.  The contact resistance may be high, or worse, the contact may act as a diode to some degree.  Feel free to experiment with modifications to this procedure; it was developed largely through trial and error.



Fabrication of metallic thin films:


Hall voltages are proportional to the sheet resistance (RS = r/d) of a sample.  Whereas semiconductor resistivity is sufficiently high to permit measurements of sizeable Hall voltages (0.01-0.1 mV) on thick samples (~0.03 cm), the resistivity of metals is so low that similar voltages can only be measured on thin films.  We use the evaporator to produce thin films of metal on a glass substrate. 




Using the electromagnet:


Always turn the water on before the power supply.  Always adjust the current slowly, and reduce it to zero before shutting off the power supply.  Wait some time before turning off the water, but remember to turn it off before you leave for the day.


Lab report guidelines:


Your lab reports should address all of the following (and may, of course, include additional information and analysis):