# Assignment help (A brief overview of the theory of the P-N junction diode)

#### garethevans177

Joined Feb 15, 2020
4
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 and my first experience of electronics, 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

#### dl324

Joined Mar 30, 2015
13,835
Welcome to AAC!

#### garethevans177

Joined Feb 15, 2020
4
Dennis, thank you for you reply. I have not started anything yet, I am still researching but I cannot find any study material that I can grasp.

#### dl324

Joined Mar 30, 2015
13,835
I am still researching but I cannot find any study material that I can grasp
If that's the case, you haven't absorbed what you were taught in class.

You should be able to predict the shape of the curve without plotting the data. Once you have the data plotted, how would you determine resistance?

#### garethevans177

Joined Feb 15, 2020
4
Dennis,

Thank you, unfortunately I don't have the luxury of attending a class and having physical contact with tutors and fellow learners that I can speak to face to face. It is a distance learning part-time degree of 6 1/2 years. I am a serving memeber of UK Armed Forces so it can be difficult to fit it all in, I'm currently 4 weeks behind due to having been away on a large training exercise. I was hoping that somebody may be able to explain PN junction diodes to me in simple, practical terms or point me in the direction of useful videos or material that will help me understand the basics as a starting point.

In order to build a true understanding I need to use more than the university provided material. My depth of background knowledge on anything electronics related is zero. I have had to learn the difference in silicon and silcone for example, basic background knowledge to try and understand what they are refering to in the material. I don't need you to tell me I haven't absorbed what I've been taught in class, I have already established this myself, that's why I am here requesting assitance of any kind, I'm not asking anyone to answer the questions for me.

#### dl324

Joined Mar 30, 2015
13,835
Forum rules require us to only offer guidance for homework. If you don't show any work, there's no point of reference to offer guidance.

Can you estimate
the resistance of this diode? How does the theory relate to the experiment?
You're being asked to do two things.

I asked you if you knew how to calculate resistance from the IV curve you were told to graph.

Apparently you've been taught some diode theory and are being asked to make a comparison.

Without the graph and your attempts at answers, we can't offer guidance.

#### crutschow

Joined Mar 14, 2008
28,537
Yes, plot the data and show us, with any questions about that.

Do you have the equation for the diode forward current versus the forward voltage?
That shows the theoretical behavior that relates to the plotted data.

#### MrChips

Joined Oct 2, 2009
25,034
Don't make the problem more difficult than needs to be.
Do the math. Plot the graph of I vs V.
And then read the first part of my blog.

#### WBahn

Joined Mar 31, 2012
26,398
Dennis, thank you for you reply. I have not started anything yet, I am still researching but I cannot find any study material that I can grasp.
Have you even tried to plot the values they gave you?

Have you tried Googling something like "PN junction theory" or "How do diodes work"?

If you can't find something that you can grasp, then you should not be taking a course like this as a distance-learning course, at least not yet.

#### OscarVaughan

Joined Aug 26, 2020
2
Have you even tried to plot the values they gave you?

Have you tried Googling something like "PN junction theory" or "How do diodes work"?

If you can't find something that you can grasp, then you should not be taking a course like this as a distance-learning course, at least not yet.
I don't think that googling will help.

#### crutschow

Joined Mar 14, 2008
28,537
I don't think that googling will help.
And likely neither will a response to a 7 month old thread.