ECE 3030: Physical Foundations of Computer
Engineering
Spring 2015
Midterm #1
12 February 2015
Prof. Vincent Mooney
Guidelines:
This exam is closed book with no programming of calculators allowed. You may
have one sheets of notes (both the front and the back of the sheet may contain notes).
Consider any violation of this policy as a violation of the Georgia Tech Honor
Code.
There are five questions. Do read the questions over before you start your work. If you
need to make any assumptions, state them. The meaning of each question should be clear,
but if something does not make any sense to you, please ask for clarification.
You Can Do It!
Name: ______________________________
Problem 1 (20 pts.)
Problem 2 (20 pts.)
Problem 3 (20 pts.)
Problem 4 (20 pts.)
Problem 5 (20 pts.)
TOTAL (100 pts.)
School of Electrical and Computer Engineering
Georgia Institute of Technology
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1)
(20 pts.)
a. (10 pts.) Determine the volume of one mole (alternatively, mol) of an ideal gas at
a temperature of 0° C and a pressure of 1 atm. Give your final answer in liters.
Note that one atmosphere (atm) = 1.01325 x 105 Pascals (P), 0 degrees Celsius
(°C) = 273.15 degrees Kelvin (K), 1 unified atomic mass unit (u) = 1 gram per
mole (g/mol), and R = 8.314 Joules per Kelvin per mol.
b. (10 pts.) Explain how the units all work out in your answer to part (a) above.
Specifically, explain the units in your starting equation and show step by step how
your answer reduces to liters. HINT: one Pascal (P) = N/m2 , one Joule = N•m,
and 1 cm3 = 1 milliliter (ml) = 10-3 liters.
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2)
(20 pts.) Explain in your own words what happens to the energy bands in the depletion
region of a PN junction – why do the bands curve in the way shown below?
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3) (20 pts.) Inference of hole concentration from an energy band diagram.
a. (10) Indicate in the diagram below which area(s) have the highest hole
concentration.
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b. (10 pts.) Given an energy band diagram, explain how one finds where the hole
concentration is the highest? What is your reasoning and how do you find where
the hole concentration is the highest? For full credit, describe the relevant
features of the energy band diagram you use to make your determination, and do
so in a clear and unambiguous way.
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4) (20 pts.)
a. (10 pts.) What does the energy gap Eg represent? Why does it exist? Please
explain in your own words what Eg represents and why it exists.
b. (10 pts.) How is it possible for light to pass through glass (SiO2 or Silicon Oxide)
unimpeded?
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5) (20 pts.) At room temperature, what is the relationship between electron concentration
and hole concentration in intrinsic Silicon? How do the relative magnitudes of electron
and hole concentrations compare with each other as temperature increases above room
temperature by, say, five degrees? For full credit, please explain your answer clearly and
unambiguously.
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THIS IS THE LAST PAGE OF THE EXAM!!!
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