Hi Niusha,

to summarize the previous answers, there is not a single way to determine (A) charge carrier type and (B) charge carrier density.

In absence of additional knowledge the carrier type (A) can only be determined by a method that breaks the symmetry with respect to electrons and holes. E.g.

1) Hall measurement (symmetry broken by magnetic field). Note that this only works reliably for "high" mobility semiconductors (mu>10cm2/Vs)

2) FET structure (symmetry broken by gate potential)

3) Non-ohmic contacts to some extent

4) Hot-probe/Seebeck (symmetry broken by thermal gradient)

To determine the carrier density (B), there are three categories:

1) Current based (FET measurements, terahertz/microwave absorption)

2) Capacitance based (C-V/Mott-Schottky)

3) Charge extraction based (CELIV, Q-DLTS)

With respect to your question (excluding Hall/Hotprobe), I would guess, that FET measurements could be most relevant for you.

Best,

Deniz

PS: I would note, that techniques based on impedance spectroscopy, usually require apriori knowledge on your system.

You can form a simple schottky junction with some metal and measure IV characteristics to know the type of semiconductor. More complicated techniques like electro chemical CV measurement can be used.

Other methods include MIS-CV, simply place some insulator and a metal on top of the unknown semiconductor and measure CV.

I m agree with Christopher

using Time-domain terahertz spectroscopy to measure the carrier density is a good method.

You can detect carrier type from the sign of the photovoltage. This can be a non contact method by using capacitive coupling of the photovoltage. Actually you can buy a unit from www.semilab.com it looks like a laser pointer.

Electrochemical impedance spectroscopy (EIS) allows you to test not only the semiconductor type but also estimate the carrier density, the flat band potential and the space charge layer width.

Impedanse spectroscopy

Sign of Zeebeck coefficient. In semiconductot it's value is large.

Seebeck effect experiment

Niusha asked for a method different to the "hot probe" method, the Seebeck effect experiment is the the "hot probe" method.

Hall Effect can be used to find the carrier concentration and also the type of a semiconductor. Here is the link

http://amrita.vlab.co.in/?sub=1&brch=282&sim=879&cnt=1

If you want to measure actual carrier concentration, (not just carrier type) and if you want to avoid making ohmic contacts, an alternative to the van der pauw/hall method is to use infrared, microwave or terahertz refection spectroscopy and fit the spectra using the drude theory. However these measurements may be applicable only to higher carrier concentrations than can be measured by the van der pauw/hall method.

If you don't want to use Hall effect, that is the best way but it requires a test pattern with four contacts at the border, an alternative measurement could be the electrical impedance spectroscopy (EIS). With this electrical measurements (Capacitance vs. Voltage) you can obtain a Mott-Shottky plot (C^ -2 vs. Voltage), a sort of data linearisation. From the slope of the curve the sign of the carrier (p-type or n-type) is obtained, as well as the flat-band voltage (the voltage at C^-2 =0) and the carrier concentration.

It depends on which kind of structures you have. One of the most simplest method is to do the CV measurement just by depositing a suitable metal on top of your Semiconductor.

I think optical pump-terahertz probe method is a good one to measure semiconductor concentration.

To Mohsen Zaim: Silicon is not the only one semiconductor presenting p-type or n-type carriers... ! Silicon wafers have their own standards, that's true, but we are talking about materials, in a general way.

Drude edge measurement.

But it did not allow to determine sign of carriers.

Hall effect measurements of course.

Hall effects measurements and C-V measurements

Hi Niusha,

to summarize the previous answers, there is not a single way to determine (A) charge carrier type and (B) charge carrier density.

In absence of additional knowledge the carrier type (A) can only be determined by a method that breaks the symmetry with respect to electrons and holes. E.g.

1) Hall measurement (symmetry broken by magnetic field). Note that this only works reliably for "high" mobility semiconductors (mu>10cm2/Vs)

2) FET structure (symmetry broken by gate potential)

3) Non-ohmic contacts to some extent

4) Hot-probe/Seebeck (symmetry broken by thermal gradient)

To determine the carrier density (B), there are three categories:

1) Current based (FET measurements, terahertz/microwave absorption)

2) Capacitance based (C-V/Mott-Schottky)

3) Charge extraction based (CELIV, Q-DLTS)

With respect to your question (excluding Hall/Hotprobe), I would guess, that FET measurements could be most relevant for you.

Best,

Deniz

PS: I would note, that techniques based on impedance spectroscopy, usually require apriori knowledge on your system.

Good summary Deniz. and Prof Gwillam is, as always, correct. My suggestions for non-contact methods are certainly not applicable in every case. However I have found that making good Ohmic contacts, Schottky junctions or FET structures is far from easy. Typically you set out to make one of them and find you made the other instead! In summary of the summary...I guess you need an array of methods to cover the wide range of doping and work functions that one can encounter in inorganic semiconductors. We did not even mention polymers!

Thank you , for your useful answers.

Hall measurement is the best simplest method to know type and concentration of dopants....Capacitance measurements are also helpful.

For strongly electron-correlated materials (including semiconductors) Hall effect may show wrong sign and/or be anomalous (AHE)

You can try with Mott-Schottky electrochemical measurements to understand the the type of your semiconductor material. From the measurements you can estimete the flat band potential, carrier density of your material and type of the semiconductor. Plot 1/C^2 vs. applied potential, you can get all these information.

HALL EFFECT

You can try to estimate the Seebeck coefficent. If it is positive you got a p-type conductor, if it's negative you have a n-type conductor. To determine the Seebeck-Coefficent is a standard meassurement in characterising thermoelectric materials.

Hi dear colleagues,

May be the best technique for measuring the type and the charge carrier concentration profiles is ECV (Electrochemical Capacitance Voltage).

Best regards

Interesting inputs all.. Mark Auslender could you please elaborate a bit on electron -correlated system and hall wrong interpretation mentioning one example. thanks!