We use the hot-probe method. One heated probe, one at room temperature.  (We
are currently investigating how small a temperature can be tolerated.) It
also appears that the probes can be very small.  At any rate, you need to
sense the polarity of the voltage developed between the probes.  If the
voltage is positive on the hot-probe, the material is n-type.  We think the
hot-probe works by the shift in the Fermi level due to temperature.
Comments for others would be very welcome.

Roger Brennan

-----Original Message-----
From: polly
Sent: Thursday, March 30, 2006 11:33 PM
To: [email protected]
Subject: [mems-talk] Conductivity type measurement

dear Sir
Please suggest me an accurate way to ascertain the conductivity type
(n-type, p-type) of the wafer.
Pourus