Transcript Slide 1

Chemistry 1410.005—INTRODUCTORY LECTURE
Fall, 2010
Instructor: Prof. J. A. Kelber (x3265; [email protected])
Office: 232 Science Research Bldg.
Office Hours T (3-5) or by appointment
Teaching Asst.: TBA
Text: Principles of Chemistry, the Molecular Science
(Moore, Stanitski and Jurs)—required
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Lecture Outline
I. About the Professor
II. About the Course
III.How to get a good grade
IV. What we will cover this
semester
V. Stuff (mainly from Chapt. 1,
but presented in a confusing
manner)
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Prof. Jeffry A. Kelber
BS (with honors) 1975, CalTech (Chemistry)
Ph.D. 1979 , Univ. of Illinois/Champaign Urbana (advisor, Prof. G. D.
Stucky)
1979-1990; member of technical staff: Sandia National Laboratories
1990-present, Chemistry Faculty, Univ. of North Texas
Current Rank: Regents Prof. of Chemistry
Publications ~ 150
Research Area: Chemistry and Physics of Surfaces and Thin Films
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About this course….YOUR GRADE
Quizzes: (10% ) every Thurs. (usually), multiple choice,
10-15 minutes each
Exams: (25% each x 2 = 50%) 1 hour, multiple choice
in class, NO EXAMS WILL BE DROPPED.
Cumulative Final (40%) Given during finals week
(12/11; 10:30 AM here)
Extra-Credit—None!
Yahoo! No Homework!!? WRONG!!!!
Homework will be assigned weekly
Homework will be discussed the following week
in recitation
Homework will NOT be Graded. However, quiz
and test questions will often be drawn from the
homework.
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How to get a good grade……………
1. Have learned and remembered something from your high
school chemistry class
(exponents, logs, trig… dimensional analysis(maybe))
2. Read the Chapter before the week it is discussed!
3. Keep up with homework, lectures, etc.
4. If you have questions or problems, consult
A. Classmates
B. Professor (if available… that’s what office hours are for,
but I will be out of town a lot)
C. The CRC
D. The TA
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What this course is about:
1. Fundamentals of chemistry
* atoms molecules chemical reactions
** Elementary understanding of chemical bonding/structure
2. Learning to think about nature
•
Memorization generally not helpful
•
Analytical skills, critical thinking important
•
Imagination and creativity
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About the exams:
1. Closed book study before the exam
2. Questions will involve analytical skills, not
memorization!
3. Do NOT memorize physical constants, etc. You will be
given that info on the exam
4. No computers, and cell phones off during the exam!
5. Calculators (no cell phones) are permitted. Should have
log, exp, trig functions
6. Exams will be hard, but graded on a curve
7. No exams will be dropped!
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Lectures and Recitations: Why Both:
Lecture:
*Emphasize and explain basic concepts
**Not all topics covered in Lecture!
***Therefore, read the book:
 Read the chapter before we begin
 Re-read the chapter after
Recitation:
*Homework and discussion
**Understanding comes from homework and quizzes
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This Semester:
Chapt. 1 Nature of Chemistry (read outside of class)
Chapt. 2
Atoms and Elements –Rutherford model of the atom, and its consequences
Chapt. 3 Chemical Compounds
Chapt. 4 Quantities of Reactants and Products (the Mole Concept, again, review for some of you)
Chapt. 5 Chemical Reactions (mainly in solution): Generally Accepted Accounting Practices for
Mother Nature.
Chapt. 6 Energy and Chemical Reactions: Why some rxns give off heat and others adsorb
it…(elementary thermodynamics)
Chapt. 7 Electronic Configurations and the Periodic Table : Rudimentary quantum mechanics,
orbitals,
Chapt. 8 Chemical Bonding : How electronic structure affects chemical bonding, periodic trends in
properties
Chapt. 9 Bonding and Molecular Structures
Chapt. 10 Gases and the Ideal Gas Law (PV = nRT)
Chapt. 11 Metals, Liquids and Semiconductors (optional)
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Travel Schedule, Fall 2013
Sept. 3-6: Portland, OR: Intel/SRC review
Sept. 23-30 Shanghai and Xi’an, China— seminars at Fudan,
Nanotechnology Conf.,
October 21-22 (?) Seminar at Univ. of Nebraska-Lincoln
Oct. 28-Nov. 1 American Vacuum Society Symposium, Long Beach, CA
Why is this necessary?
1. Communication of research
2. Obtaining financial resources to support more (graduate and
undergraduate) students doing research…
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A word about memorization…. Forget it!
Science puts a premium on imagination and deduction
You will be asked to think quite a bit, rather than memorize formulae.
Tests will be multiple choice and open book, but NOT easy
WORK THE HOMEWORK PROBLEMS YOURSELF, THEN (IF
NECESSARY) GET HELP:
FROM YOUR TA
FROM THE CRC
FROM YOUR PROFESSOR
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The Development of Modern
Chemistry
Atomic theory
(Dalton,1803)
Boltzmann,
kinetic theory
of gases (1870’s)
Bardeen, Brattain, Schockley,
Transistor (1947)
Planck,
quanta, 1900
Haber, Langumir: Catalysis
and surface chemistry
J. J. Thomson,
discovery of the
electron (1897)
DeBroglie, Davisson and
Germer, wave nature of
the electron (1925-27)
Rutherford
model of the
atom (1913)
1900
1800
Dalton, Henry
Electricity and
magnetism
Mendeleev,
periodic
table (1871)
Atomic theory, classical physics
Atom Bomb (1945)
Pauling, Mulliken, et
al. chemical bonding
Chemical bonding and
nuclear physics/chemistry
B ohr model
(1913)
Heisenberg, Schroedinger,
Dirac, Born New quantum
theory (1925-30)
Einstein,
photoelectric
effect (1905)
Quantum theory
Crick,
Watson,
Franklin
DNA double
Helix (1952)
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1952, Teal and Buehler (Bell Labs) publish paper on production of
ultra pure Si; the modern transistor is born
1947, Bardeen, Shockley and Brattain, form a research group
at Bell Labs to develop solid state switches and amplifiers:
Develop the modern transistor using germanium!
1925-1945: Birth of solid state physics,
chemistry; understanding the behaviors of
electrons in solids
Mott, Pierls, Pauling, Seitz solid
state physics
1925: Birth of the new quantum theory;
Understanding electrons in matter
The “Invention”
of the
Transistor
1913: Rutherford model of the
atom/ Bohr Theory
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1900: Planck/quantized photon energy
Moral: Most Great modern “inventions” are not really invented…
They are the culmination many different advances.
Max Planck had no idea that quantum physics would yield the
transistor and …
high speed computing
molecular biology
lasers
modern metallurgy
the internet Facebook(!?)
and………
Do Funding Officers and Agencies understand this? Not always!
Example: The “war” on cancer:
We spend lots of money on minor clinical advances, but
underfund basic research that could lead to real
breakthroughs (NYT-2009)
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Since 1947: The morphing of the
transistor:
From electronics to microelectronics to
nanoelectronics
1 transistor/chip 1 billion/chip
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Moore’s ‘Law’
# of Transistors
on a chip doubles
~ every 2 years
(Moore’s Law):
Transistors (and
interconnects)
need to get
smaller!
From IEEE.org/Intel Logic devices
Number of transistors on a chip > 1 x 109
= 1,000,000,000 (1 billion) (one followed by 9 zeroes)
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The modern field-effect Transistor
I
Vapp
Gate oxide
thickness
(d) ~ 1 nm
Vapp
e-
Channel length (L) =65 nm
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http://commons.wikimedia.org/wiki/File:Scheme_of_metal_oxide_semicon
ductor_field-effect_transistor.svg
What are nanometers? Atomic diameters?
Scientific Notation?
Dimensional Analysis???
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Let’s consider a piece of Si about ½ inch x ½ inch:
0.5 in
= 5 x 10-1 in
0.5 in = 5 x
10-1 in
What’s the total area?
A = LxW = 0.5 in x 0.5 in = 5 x 10-1 in x 5 x 10-1 in
= (rearranging) 5 x 5 x 10-1 x 10-1 in x in
NOTE 10A x 10B = 10A+B therefore,
A = 25 x
10-2
in2
= 2.5 x
10-1
in2
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Dimensional Analysis:
How can we convert from in2 to cm2?
Conversion Factor: 1 in = 2.54 cm
1 in2 = 1 in x 1 in = (1 in x 2.54 cm/in) x (1 in x 2.54 cm/in)
= 2.54 x 2.54 cm2 = 6.45 cm2
Our chip has a total area of 6.45 cm2
6.45 cm2
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There are ~ 1 billion (1 x 109) transistors on a chip.
What is the average area of each transistor?
We want answer in terms of cm2/transistor. So let’s divide the
total chip area by the number of transistors!
Area/transistor = [total chip area]/[109 transistors] =
6.54 x 10-9 cm2/transistor
This is a bit hard to visualize, so let’s convert to
atomic dimensions and then to atoms!
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Let’s try units of nanometers (nm)
1 cm = 10-2 meters (m); 1 m = 102 cm
1 nm = 10-9 m x 102 cm/m = 10-7 cm
1 nm2 = (10-7 cm) x (10-7 cm) = 10-14 cm2
Area/transistor = 6.54 x 10-9 cm2/transistor / [10-14 cm2/nm2]
= 6.54 x 10-9 x 1014 nm2/transistor = 6.54 x 105 nm2/transistor
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About how many Si atoms is that?
Fact: Areal Density of Si atoms on Si(100) is ~ 1015 atoms/cm2
1015 atoms/cm2 x [10-7 cm/nm]2 x 6.54 x105 nm2
= 1015 atoms/cm2 x 10-14 cm2/nm2 x 6.54 x 105 nm2
= 6.54 x 106 atoms/transistor (estimate) ~ 107 atoms/transistor
This sounds like a lot, but the number of atomic diameters for the L and
W of a transistor is then ~ √107 = (107)1/2 atoms on a side!
(107)1/2 = (10 x 106)1/2 = (10)1/2 x (106)1/2
~ 3.12 x 103 atoms on a side
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transistor
1000 atoms
1000 atoms
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Transistors get smaller….
Channel length 65
nm =650 angstroms:
~ 200-300 atomic
diameters!!!
Gate oxide < 1.2 nm
thick ~ 5 silicon
atoms thick!
From IEEE.org/Intel logic Devices
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What happens at atomic dimensions…
Oxide thickness ~ electron wavelength (d ~λ)
The electron “leaks out”: Leakage current lowers battery life, limits on/off state
detection.
e-
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What to do? Change gate oxide from SiO2 to HfSiOx (Hafnium silicate)
Greater polarizeability oxide can be made thicker! (long story…)
First research papers…1990’s (e.g., review by Wilk and Wallace, 1999)
In production…2008
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This invention took two decades and lots of people!
About the Future….?
Continued shrinkage of transistor dimensions hindered by
wave nature of electrons (λ d)
Can we develop materials/devices that take advantage of the
quantum behavior of electrons???
Single atomic layer of
graphite “graphene”
Rapid electron conduction
at room temperature
lbl.gov
Many other amazing
properties (see Geim, et al;
also deHeer group,
Georgia Tech/2004), also
an episode of TV’s “Big
Bang Theory”)
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Beyond the Transistor:
Non-volatile logic/memory elements:
Based on spin? (Graphene instead of
InAs??)
S. Suguhara and J. Nitta; Proc. IEEE 98 , 2125 (2010)
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Beyond the transistor and spin-transistor: logic gates based on spin
devices (Here, magnetic tunnel junctions)
Velev, et al., Surf. Sci. Rep.63, 400
(2008)
Richter, et al: Appl. Phys. Lett. 80, 1291 (2002)
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Summary:
Scientific Discovery is a Long Road, and no one
knows where it will lead.
(You can’t predict the future!)
The Transistor took 50 years, and the end is not
in sight
**new materials
***spin vs. charge (spintronics)
****neural networks (networks that learn)
????????
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Conclusion:
1. Memorization? ….fughedaboudit! (Tony Soprano)
2. You should know or learn:
dimensional analysis
scientific notation
get a feel for problem solving
Example…..
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1 cm
1015 Si atoms
Question: Given that the
areal density of Si is 1015
atoms/cm2,
Estimate the atomic
diameter of a Si atom in
angstroms
1 cm
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Second Problem:
Mass of a hydrogen atom: 1 atomic mass unit (amu)
Mass of 1 mole of atomic H: 1 gr.
1 mole of anything = 6.02 x 1023 of those things.
Problem 2: calculate the mass of a H atom in grams
From Chapter 1
Probs. 14, 26, 27, 63
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For Tuesday
1. Work assigned problems (handout)
1. Read Chapts 1 and 2 of text
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