If you have a junction either hetero or homo and you want to measure its C-V curve , you have to be sure that the parasetic resistances of the diode will not affect the measurement. So, we choose to bias the junction in the reverse bias to avoid the effect of the conduction resistance of the diode in the forward bias. The other effect comes from the parasitic series resistance of the diode due to bulk resistance of its reaistance Rs. Normally Rs is relatively small. So, basically one has to choose a frequency such such that Rs must be much smaller than 1/wC, where w is the angular frequency of the applied signal and C is the junction capacitance. So, w must be much smaller than 1/RsC. Most rlc meters gives resistive part and the reactive part of the measured impedance. So you can easily adjust the measuring frequency such that the reactive part is much greater than the resistive part of the diode impedance.

Best wishes

If you have a junction either hetero or homo and you want to measure its C-V curve , you have to be sure that the parasetic resistances of the diode will not affect the measurement. So, we choose to bias the junction in the reverse bias to avoid the effect of the conduction resistance of the diode in the forward bias. The other effect comes from the parasitic series resistance of the diode due to bulk resistance of its reaistance Rs. Normally Rs is relatively small. So, basically one has to choose a frequency such such that Rs must be much smaller than 1/wC, where w is the angular frequency of the applied signal and C is the junction capacitance. So, w must be much smaller than 1/RsC. Most rlc meters gives resistive part and the reactive part of the measured impedance. So you can easily adjust the measuring frequency such that the reactive part is much greater than the resistive part of the diode impedance.

Best wishes

Dear Oualid,

I want that you follow the paper in the link:https://www.researchgate.net/publication/3061263_Capacitance_and_conductance_of_ZnxCd1-xSZnTe_heterojunctions.

This paper investigates the dependence of the heterojunction capacitance and conductance on frequency. I think it may be useful to you.

Best wishes 

Article Capacitance and conductance of ZnxCd1-xS/ZnTe heterojunctions

Thank you dear Dr.Abdelhalim Zekry.

 Dear Oualid;

the attached files might help you............

https://www.researchgate.net/publication/258245967_Photoelectrochemical_Methods_for_the_Determination_of_the_Band_Edge_Positions_of_TiO2-Based_Nanomaterials

https://www.researchgate.net/publication/272360981_Structural_distortion_in_graphitic-C3N4_realizing_efficient_photoreactivity

http://iopscience.iop.org/article/10.1088/0957-4484/24/25/255601

best regards

Article (Photo)electrochemical Methods for the Determination of the ...

Article Structural distortion in graphitic-C3N4 realizing efficient ...

@ Abdelhalim Zekry

Sir, Can you please help me in making the device structure for TiO2 on FTO for calculating Mott Schottky , i meant to ask how to make contacts on FTO for calculating donor density .