In order to determine the doping type of silicon, we are using two probes
with one heated slightly. We are using op-amps to amplify and record the
polarity of the Seebeck voltage generated by the temperature difference
under the probes.  Can anyone suggest a better way of determining the
polarity of this very minute voltage?  Are there ICs or instruments that
specifically address voltage polarity rather than magnitude?

Thanks in advance,

Roger Brennan