I have been fabricating TCO of Zinc and its doped variants.But I have not come across any method of conductivity measurement,just conductance values in literature.
Conductivity measurements depends whether your conductivity is low or high. For low resistance upto a few ohms measurements in thin films four probe technique has to be used as two probe technique gives wrong measurement due to contact resistance which may be comparable to the resistance of your sample. However, when your resistance is high in kohms and above, two probe technique is preferred.For high resistance measurements, special care has to be taken to electromagnetically shield the test sample and high input impedance of electrometer, proper shielded cable for connection. If you are having transparent conducting films, you can you use four probe technique to measure the potential drop between two electrodes when a constant known current flows between other two electrodes and then calculating conductivity using the geometry of electrodes.
Thank you Sir,ZnO conductivity range from literature falls under semiconductors,while doping them was to increase its electron mobility.Does other factors such as film thickness play a major role in conductivity,if we use four probe technique.Our film thickness falls in several hundred nanometer (close to 700-800nm).
Dear Prince,
For the calculation of sheet resistance, only the values of I and V are required. However, to calculate conductivity you need the thickness of the film. Many workers have used four probe method for calculating conductivity in conducting polymers and other conducting films. You can go through the Google search to find these details.
In case you don't have a bar shaped sample but, rather, a square (or any shape), you can use the Van der Pauw method (it is actually a 4 probe method) to find rhe sheet resistance. As it was already mentioned, knowing the thickness gives you the resistivity. If you have access to a magnet you can measure the hall coefficient and, thus, get mobility, sign of carriers and number of carriers.
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