Using Hall effect you can determine the type of carrier concentration

Dear Vinothkumar,

how Ishan wrote, Hall effect is the ultimate method .But you have to take into account some pitfalls. If you have only one kind of carriers, the Hall voltage U can be calculated by

U = IB/(e*n*d)

with I the current through the sample, B the magnetic field strength (induction!), e the elementary charge, d the sample thickness and n the carrier concentration.

Roughly rule:

If U is positive, than you have a p-type, otherwise it is a n-type.

Some important hints:

Because you easy can interchange the contacts for voltage measurements: We use a reference sample, for instance a high doped p-type or n-type Si-sample with known concentration to prevent errors.

If you use low doped samples, the upper formulae can be invalid. Here the mobility ratio is important, because you can have contributions of electrons and holes.

Hall voltages can be small. Avoid thermovoltages and noise voltages. We ever measure U as a function of B in the negative and positive field range and determine the slope of this curve.

Forget never: The sign can be influenced by a lot of effects.

With Regard

R. Mitdank

Thanks for answer Prof. Rüdiger Mitdank

Thanks for the note Dr. Ishan Choudhary

Hello Vinothkumar,

in addition to my upper remarks I want to recommend an alternative method. This is the use of a so called "Kelvin probe". This probe is used to determine contact potential differences. Nevertheless it can be used to detect the dopand type of materials. I didn't myself use this method but it seems to work. Please look the citations I send to you.

Yours

R. Mitdank

Off course, Hall effect is not the ultimate tool. This is one of the measurement techniques for the same. For oxide semiconductor a fine control over the measurement is required. A lot of factors affect this measurement, Major hurdles in this measurement is misalignment voltage and low Hall voltages which Rüdiger Mitdank mentioned above. For dealing with misalignment voltages samples dimensions and pattern plays major role. If you are interested in this measurement i suggest you to read this Book "SEMICONDUCTOR MATERIAL AND DEVICE CHARACTERIZATION" written by DIETER K. SCHRODER (Arizona State University) first before proceeding with this measurement. This deals with the pitfalls of the measurement and suggests the possible ways to overcome those.

Secondly, you can always have a option to calculate the expected hall voltage by reverse engineering the calculations. Choose your voltmeter and current source in accordance to that, which can measure such voltages.

Also, this is one of the technique, you can try other techniques as well as mentioned by Rüdiger Mitdank. if you get results from Hall Effect as well, it will support your findings.

Best of luck for your work.

Thanks all for the citations and books.

Thanks lot