Page 82 - Photonics Essentials an introduction with experiments

Electrical Response Time of Diodes

76 Photonic Devices

Make a plot of capacitance versus carrier concentration using
a log-log scale. There will be four curves corresponding to the
four voltages. Put a copy of this graph in your lab book.
2
4.3 Using the data in Table 4.1, make a plot of (C /A ) versus bias
2 –1
voltage. Determine the built-in voltage using this plot.
4.4 The series resistance of a p-n diode and its capacitance are both
determined primarily by the characteristics of the lightly doped
side of the junction.
a. Show that the RC time constant of a p-n junction photodiode
in reverse bias is independent of the diode area.
b. Why is it generally true that a diode with a smaller surface
area will have a faster time response? (Hint: There are two
resistances: the diode resistance and the circuit resistance.
What determines the overall resistance?)

Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com)
Copyright © 2004 The McGraw-Hill Companies. All rights reserved.
Any use is subject to the Terms of Use as given at the website.