Need the following:

|Title|ISBN-13|Bounty|
|:-|:-|:-|
|Intro To Semiconductor Devices|9780072987560|$5|
|Introduction to Communication Systems SOLUTION MANUAL|Book ISBN: 9781107022775 [Since no ISBN exists for Solution Manual that I know of.]|$5|

Ahh, then perhaps try another book (or wikipedia, which tends to have good explanations). I can recommend:

Hu - Modern Semiconductor Devices for Integrated Circuits

http://www.eecs.berkeley.edu/~hu/Book-Chapters-and-Lecture-Slides-download.html

Sze - Physics of Semiconductor Devices

http://www.amazon.com/Physics-Semiconductor-Devices-Simon-Sze/dp/0471143235

Kasap - Principles of Electronic Materials and Devices

http://www.amazon.com/Principles-Electronic-Materials-Devices-Kasap/dp/0073104647/

Neamen - An Introduction to Semiconductor Devices

http://www.amazon.com/Introduction-Semiconductor-Devices-Donald-Neamen/dp/0072987561/

And for entertainment value, Britney Spears' Guide to Semiconductor Physics:

http://britneyspears.ac/lasers.htm

If these aren't available in your library, you can find perfectly good older editions at abebooks.com for less than $20 with shipping.

The semiconductor will always be at equilibrium ( n*p = n_i) unless acted on by an external energy source, such as a bias voltage or light source. No external source = equilibrium.

https://www.amazon.com/Introduction-Semiconductor-Devices-Donald-Neamen/dp/0072987561