ECE344 Fa1112
HOMEWORK 5
|2pts Let us consider a Silicon nMOS capacitor with the following values: NA = 7 x llcm3, T 2
300K, WM = X6_ = 4.05eV, tax = 3flnm, em = 3.45 >< 10'11F/m. Find (a) the value of the
atband voltage, (b) the threshold voltage, (0)
ECE344 Semiconductor Devices
Fall 2012
QUIZ-3
A silicon material maintained at 300K is characterized by the following energy
band diagram:
'5
P
.
1 I
:f/ i
I '.
I I
I i
' I
' l
1,.
w- - "4 ' # .Er
i=0 XL
Question 1 (10pts)
[1 pt] Is the mater
ECE344: Semiconductor
Materials and Devices:
Bipolar Junction Transistors (BJTs)
Zlatan Aksamija
zlatana@engin.umass.edu
Midterm exam grade distribution
Cumulative grade distribution so far
The Bipolar Junction Transistorintroduction
In simplest terms, a
ECE344: Semiconductor
Materials and Devices:
P-N Junction I-V curves
Zlatan Aksamija
zlatana@engin.umass.edu
The p-n junction in equilibriumcurrents
The drift currents are both (JN|drift and JP|drift) going right-to-left
Diffusion currents (JN|diff and
ECE344: Semiconductor Materials
and Devices:
Metal-Oxide-Semiconductor Field
Effect Transistors (MOSFETs)
Zlatan Aksamija
zlatana@engin.umass.edu
Blue Waters Student Internship Program
NSF support for undergraduate internships involving high-performance
ECE344: Semiconductor Materials
and Devices:
Metal-Oxide-Semiconductor (MOS)
Zlatan Aksamija
zlatana@engin.umass.edu
The rest of the semestera preview
Since the midterm exam, we have covered:
P-N junction diodes: deviations from the ideal diode law (Cha
Welcome to ECE344:
Semiconductor Materials and
Devices
Zlatan Aksamija
zlatana@engine.umass.edu
At the dawn of time
First there were vacuum tubes
Invented in 1904 by John Ambrose Fleming
Diodes, triodes, pentodes, miniatures
Still used for extreme environ
ECE344: Semiconductor
Materials and Devices:
Crystal Structure
Zlatan Aksamija
zlatana@engin.umass.edu
Online resources: NanoHUB.org
The NanoHUB is an excellent resource providing an on-line community portal
Link available on our Moodle course webpage
ECE344: Semiconductor
Materials and Devices:
P-N Junction Electrostatics
Zlatan Aksamija
zlatana@engin.umass.edu
Poissons equation
Relates charge (not carrier) density to the slope (or gradient in 3d) of the E-field
=
()
0
or in 3D
=
(,)
0
(5.2 and 5.
ECE344: Semiconductor
Materials and Devices:
Carrier Action
Zlatan Aksamija
zlatana@engin.umass.edu
4 Types of Carrier Action
We have discussed carrier concentrations in equilibrium
Now we wish to develop a picture of what they do in/near equilibrium
1.
ECE344 Midterm Exam
November 18, 2005
1. Problem. Consider a sample of silicon at T = 300 K. Assume that the electron
concentration varies linearly from n(0) at x = 0 to 5 1014 cm3 at x = 0.01 cm.
The diusion current density is measured to be jn = 0.19 A/
ECE344 Practice Problems for Midterm Exam 2
November 15, 2005
1. Problem. An n-type silicon sample has a resistivity of 5 .cm at T = 300 K.
Assume that the electron mobility at this temperature is 1,500 cm2 /Vs and that
the mobility varies as T 3/2 .
(a)
ECE344, Midterm Exam 1: Solutions
October 19, 2009
1. Problem: The workfunction of a material is dened as the energy required to
remove an electron from the material and is usually indicated by the Greek letter
(pron: khi).
The workfunction of gold is Au
ECE344: Practice questions for Midterm Exam 1:
Solutions, October 13, 2009
1. Problem. a. An electron is moving with a velocity of 2 106 cm/s. Determine
the electron energy in eV, its momentum, and de Broglie wavelength in nm.
b. The de Broglie wavelength
Homework 7
1. Problem: (a) Consider an n-channel MOSFET with uniform channel doping with NA = 3 1017 cm3 and
having an oxide 10 nm thick. Calculate the sub-threshold slope at 300 K.
(b) Assume now that the Si-SiO2 interface is not ideal, but there are int
Homework 6
1. Problem:
(a) Using the gures on pages 133 and 134 of the Lecture Notes, Part II, as a guide, sketch the band diagram
of an MOS capacitor with an n-type Si substrate in i) accumulation, ii) at at band condition, and iii) at the
onset of stron
Homework 5
1. Problem: A silicon p-n junction is formed between n-type Si doped with ND = 1017 cm3 and p-type Si
doped with NA = 1016 cm3 .
(a) Sketch the energy band diagram. Label all axes and all important energy levels.
(b) Find nn0 , np0 , pp0 , and
Homework 4
1. Problem: Find the resistivity (in ohm-cm) for a piece of Si doped with both acceptors (NA = 1019 cm3 )
and donors (ND = 1016 cm3 ). Since the electron and hole mobilities depend on the concentration of the
dopants, use the following empriric
Homework 3
1. Problem. Calculate the value of the Fermi level and sketch its position in a band diagram for the following
cases:
a. Ge, n-type, ND = 1017 cm3 , T = 300 K.
b. Si, p-type, NA = 2 1018 cm3 , T = 450 K.
c. GaAs, n-type, ND = 1018 cm3 , NA = 5
Homework 2
1. Problem.
The atomic weight A of the only stable isotope of As is 75. There are two stable isotopes of Ga: One of atomic
weight 69, occurring with 60.4% abundance. The second isotope has A=71, with natural abundance 39.6%.
The atomic mass uni
Homework 1
1. Problem: Streetman, Sixth Ed., Problem 2.2:
Show that the third Bohr postulate, Eq. (2-5) (that is, that the angular momentum p around the polar axis
is an integer multiple of the reduced Planck constant h, so p = nh) is equivalent to an int