Determining Ideality Factor and Reverse Saturation Current

In summary, to determine the ideality factor and reverse saturation current of a diode, one can use a circuit to record current and voltage values and plot the I versus V relationship on a semilog graph paper. The slope of the ln I versus V plot can be used to calculate the ideality factor, and the y-intercept can be used to calculate the reverse saturation current. An extension to this experiment could involve varying the temperature or using a diode with a known coefficient A to determine the coefficient A in equation 6.
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Homework Statement


Ideality factor and reverse saturation current

http://3.bp.blogspot.com/_h90yJnbZXIE/SfMcs8FCF8I/AAAAAAAAAFk/dJ7cnqLGntk/s1600-h/circuit_fordiodeparameterextraction.JPG
Use the circuit above to determine the I-V characteristic over 3 decades of current from 0.01 mA to 10 mA. Record the current and voltage values using the two DMMs and plot the I versus V date on a semilog graph paper.

Explain how you can determine the slope of the ln I versus V relationship from the semilog plot. From this graph, determine the ideality factor n and reverse saturation current I0.

I0 = 0.3nA (y-intercept of the graph from the semilog plot)
Gradient of ln I against V graph: q/nKT=ln⁡〖(9×〖10〗^3 )-ln⁡50 〗/(0.4-0.2)=25.96=26.0
Ideality factor, n=q/(26.0)KT=1/(26.0×0.0252)=1.53

Homework Equations



This is where I stuck:

Suggest an extension to this experiment by which the coefficient A of a diode in equation 6 can be determined

I0 =AT^3 e^((-Eg)/kT) (6)

PLease help!
 
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it is important to always think about ways to improve and extend experiments to gather more accurate and comprehensive data. In this case, one possible extension to this experiment could be to vary the temperature and observe its effect on the ideality factor and reverse saturation current.

To determine the coefficient A in equation 6, one could perform the same experiment at different temperatures and plot the ln I versus V relationship for each temperature. The slope of each plot would correspond to the value of q/nKT at that specific temperature. By plotting the value of q/nKT against temperature, one could then use the Arrhenius equation (ln(A) = ln(I0) + (-Eg)/kT) to calculate the coefficient A.

Another way to determine the coefficient A could be to use a diode with a known coefficient A and compare its I-V characteristic with the one obtained from the experiment. By adjusting the temperature and plotting the ln I versus V relationship for both diodes, the values of q/nKT can be compared and the coefficient A can be determined.

Overall, by extending the experiment to include temperature variation or using a diode with a known coefficient A, the accuracy and reliability of the data can be improved, leading to a more accurate determination of the ideality factor and reverse saturation current.
 

1. What is the ideality factor?

The ideality factor is a measure of how closely a diode or semiconductor device follows the ideal diode equation. It takes into account deviations from ideal behavior due to factors such as recombination and series resistance.

2. How is the ideality factor determined?

The ideality factor can be determined by plotting the logarithm of the diode current against the diode voltage and calculating the slope of the resulting curve. The intercept on the voltage axis gives the reverse saturation current, and the slope is equal to the ideality factor.

3. What is the significance of the ideality factor?

The ideality factor provides information about the quality of the diode or semiconductor device. A lower ideality factor indicates a device with fewer deviations from ideal behavior, while a higher ideality factor suggests the presence of defects or imperfections.

4. What is reverse saturation current?

Reverse saturation current, also known as leakage current, is the small current that flows in the opposite direction of the forward current in a diode when a reverse bias voltage is applied. It is caused by minority carriers in the semiconductor material and is affected by temperature and doping levels.

5. How is reverse saturation current related to the ideality factor?

The ideality factor and reverse saturation current are related through the ideal diode equation, which states that the diode current is equal to the reverse saturation current multiplied by the exponential of the diode voltage divided by the thermal voltage. The ideality factor appears as a coefficient in the exponential term.

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