Exercise 3.13 (Sedra/Smith)
For a PN junction with Na=10¹⁷ / cm³ and Nd=10¹⁶ / cm³ find at T=300K the built in voltage the depletion width and the distance it extends into the p-side and n-side of the junction . Use ni=10¹⁰ / cm³.

Objectives:
Upon completion of this laboratory students should be able to understand the physical meaning of the parameters and to calculate the built-in voltage depletion width and the extent of depletion in the n and p side of the semiconductors using the applet.

Pre-lab(Hand Calculation)
1) For a PN junction with Na=10¹⁷/cm³ , Nd=10¹⁶/cm³ and T=300K
a. Find built in voltage, Vo
b. The width of the depletion region., W_d
c. The distance it extends on the n and p side , x_n and x_p.

Procedure using Applets in the Lab:

1) Visit the virtual lab at the URL: http://jas.eng.buffalo.edu/education/pn/pnformation_B/index.html
2) This applet lets you visualize the following processes in a semiconductor :
Formation of the junction
The extent of channel on the n and p side
The  width of the channel.

Applet procedure

3) Fill in the textboxes(At the bottom of the applet) with the values of Na and Nd given in the problem

4) Click on  the setNewValue button in the applet to set the new values of Na and Nd
       that you have just filled in the boxes.

5) Make sure that the material of the device is set to silicon.

6) Now click on the FormJunction button to see the junction formation process.

7) At the end of the animation you read the values of    xn=....... ...mm. and  xp=.........mm... from the applet and hence the value Wd= xn+xp=.............. ?m using the button ShowParameters.

8) You can also view the band diagram from which you find Vo =............V

9)At the end of the session you may try out to different values of a Na and Nd
b) Na = Nd     b) Na >Nd  and    c) Na <Nd and look at the values of depletion width
     band gap energy etc.