In four doped samples the series resistance of the samples was increased with the increasing the dopant percentage, but the I-V results show at a particular voltage the current was increased by these percentages of dopant (it means that the sheet resistance was decreased). How to explain this subject.
Dear Farid Jamali Sheini ,
welcome!
I will give a conceptual answer and you review your question and measurements according to my answer.
The doping has two effects:
- increasing the mobile carrier concentration n such that normally n is proportional to N (the doping).
-The other effect is that it decreases the mobility of mobile and remain neural charges
For metallic materials such as silicon the conductivity will mostly increase with the doping as the increase in n over weight the decrease in the mobility.
There are deviations from these rules:
When the dopant atoms are not easy to ionize and remain neutral so they will not increase n but decrease the mobility. In this case the conductivity decreases with the doping.
When one heats up the specimen the neutral impurity atoms and they gets ionized so the conductivity will increase by increasing the temperature.
It can be that as you increase the voltage the power dissipated in the specimen increases and the temperature gets higher ionizing more and producing more mobile charges which can decrease the resistivity,.
This may be some scenario for the behavior pf your material.
please comment!
Best wishes
Dear Farid Jamali Sheini ,
welcome!
I will give a conceptual answer and you review your question and measurements according to my answer.
The doping has two effects:
- increasing the mobile carrier concentration n such that normally n is proportional to N (the doping).
-The other effect is that it decreases the mobility of mobile and remain neural charges
For metallic materials such as silicon the conductivity will mostly increase with the doping as the increase in n over weight the decrease in the mobility.
There are deviations from these rules:
When the dopant atoms are not easy to ionize and remain neutral so they will not increase n but decrease the mobility. In this case the conductivity decreases with the doping.
When one heats up the specimen the neutral impurity atoms and they gets ionized so the conductivity will increase by increasing the temperature.
It can be that as you increase the voltage the power dissipated in the specimen increases and the temperature gets higher ionizing more and producing more mobile charges which can decrease the resistivity,.
This may be some scenario for the behavior pf your material.
please comment!
Best wishes
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