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Assignment help (A Brief overview of the theory of the P-N junction diode).

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garethevans177:
Hello,
 
Could anyone please help, as part of my foundation degree mechanical systems engineering, I am currently working on my electronics module. As it is a distance learning degree I am finding it difficult to grasp. Could any one help me in any way with the following question?

P-N junction forward bias characteristics
The diagram in figure 1 provides the voltage and current measurements shown in table 1.
Figure 1
Table 1
Give a brief overview of the theory of the P-N junction diode. Plot the data generated in
table 1 using Microsoft Excel. Extrapolate the straight-line part of the graph to intercept
the voltage axis and estimate the turn on voltage for the diode tested. Can you estimate
the resistance of this diode? How does the theory relate to the experiment?
V1
D1
1N4148
XMM1
XMM2
Vd (V) Id (A)
0 0
0.1 1.04E-10
0.2 4.28E-10
0.3 1.12E-08
0.4 5.21E-07
0.5 2.40E-05
0.6 1.09E-03
0.7 1.83E-02
0.8 6.13E-02
0.9 1.14E-01
1 1.70E-01

rstofer:
This w2aew video may help



rstofer:
Here is the spreadsheet.  I didn't add all the fancy labels because graphs with Excel are a PITA.  Learn MATLAB or, for free, learn Octave, an opensource work-alike.

In any event, it shows the characteristic curve we expect as a diode gets increasingly forward biased.  Print the graph and just use a pencil and straightedge to estimate the resistance R = E / I.  You pick a couple of points on the slope of the line, figure out the change in current and the change in forward voltage.  Do a little division and you get the dynamic resistance.  It will be a low value of Ohms.  Around 4:30 in the video...

As to the theory of the junction, that stuff is all over the Internet.


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