Transcript
Nanoscience and Energy Allen Hermann, Ph.D.
Professor of Physics Emeritus, University of Colorado
Boulder, Colorado 80309-0390 USA
allen.hermann@colorado.edu
Lecture 1. Course Introduction and Definitions
History, and examples
in nature and man-made
Quantum nature- theory:
quantum confinement
Nanomaterials: Dimensionality
Chemical varieties and shapes
Synthesis
Top-down: Lithography
Bottom-up: Self-assembly
Characterization and Handling
Measurements
Nanotemplates
Lecture 2. Nanocarbon C60, CNT’s
Synthesis and e-beam lithography
Graphene (synthesis, relativistic
QM nature, transport)
Lecture 3. Energy and Nanotechnology Review of Alternate Energy
Sources
Review of Electronic Properties of
Solids:
Free- electron Fermi gas
Energy bands in Solids
Semiconductors and doping
pn junctions
Amorphous semiconductors
Lecture 4. Solar cells: Motivation (examples) and Theory pn junctions under illumination
Homojunctions
Open-circuit voltage, short-
circuit current
IV curve, fill factor, solar-to-
electric conversion efficiency
Carrier generation and
recombination
Defects and minority carrier
diffusion
Current due to minority carrier
diffusion:
Solution to the diffusion
differential equation under
Spatially-homogeneous
generation, and
under Inhomogeneous
generation
Effect of an electric field
Heterojunctions
Lecture 5. Experiment: Types of Solar Cells
•Generation I solar cells:
Single Crystal Si, Polycrystalline Si
Growth, impurity diffusion, contacts, anti-reflection coatings
•Generation II Solar cells:
Polycrystalline thin films, crystal structure, deposition techniques
CdS/CdTe (II-VI) cells
CdS/Cu(InGa)Se2 cells
Amorphous Si:H cells
•Generation III Solar Cells:
•High-Efficiency Multijunction Concentrator Solar cells based on
III-V’s and III-V ternary analogues
•Dye-sensitized solar cell
•Organic (excitonic) cells
•Polymeric cells
•Nanostructured Solar Cells including Multicarrier per photon cells,
quantum dot and quantum-confined cells
Lecture 6. Nanotechnology Fuel Cells
Nano-composite materials
Nanoelectronics and photonic
Devices:
Chemical and Biological Detectors
Nanomedicine:
Disease Detection
Implants
Delivery of Therapeutics
Other nanomedicine
Applications
Risks
Lecture 7. Other Nanotechnology Applications DNA sequencing
Filtration
Clothing and Sports
Composites
Other Nanomedicine Applications and Opportunities
Other Nanotemplate-based Applications:
Superconductors
Magnetic Nanowires
Ferroelectrics
Dielectric Nanostructures and Cloaking
The Business of Nanotechnology
Basis for Grade in the Course
Your grade in the course is based on 2 factors:
1) class attendance 2)grade earned on the paper
assigned.
A 1-2 page paper in English is to be turned in to Prof. Hermann by the end of the last lecture. Both a hard
copy and a digital copy emailed to allen.hermann@colorado.edu
are required. This paper should be in your own words.
The paper could contain one or more figures and/or tables.
The subject matter should be either 1) a tutorial explaining clearly one topic from this
course (in greater detail than given in the course), or 2) a clear description of your own research related
to the subject of this course.
Your grade will be calculated as follows: Attendance- 40% ( 5.71 % per class attended) Grade for paper- 60%
Further References1. Charles Kittel, “Introduction to Solid State Physics”, Prentice Hall (1967 ff.)2. S.M. Sze, “Physics of Semiconducting Devices”, John Wiley (1969,ff.)3.Frank Larin, “Radiation Effects in Semiconducting Devices” (John Wiley)4. H.Y. Tada and J.R. Carter, JPL Solar cell Radiation handbook, NASA (1977)5. Martin Green, “Solar Cells”, Prentice Hall (1982,ff.)6. H.J. Hovel, “Solar Cells”, in Semiconductors and Semimetals, Vol.11 (edited by R. Richardson and A. Beer, Academic Press, 1975).7. J. Reynolds and A. Meulenberg, J.Appl. Phys. 45, 2582(1974)
Lecture 1
Course Introduction and Definitions
Lecture 1. Course Introduction and Definitions
History, and examples
in nature and man-made
Quantum nature- theory:
quantum confinement
Nanomaterials: Dimensionality
Chemical varieties and shapes
Synthesis
Top-down: Lithography
Bottom-up: Self-assembly
Characterization and Handling
Measurements
Nanotemplates
10,000 Kilometers
1000 km
Sliding scale universe: http://htwins.net/scale2/scale2.swf?bordercolor=white
What is Nanotechnology?
• Research and technology development at the atomic, molecular
or macromolecular levels, in the length scale of approximately 1 - 100 nanometers.
• Creating and using structures, devices and systems that have novel properties and functions because of their small and/or intermediate size.
• Ability to control processes at a few nm-range for advanced material processing and manufacturing.
Red blood cells (~7-8 mm)
DNA
~2-1/2 nm diameter
Things Natural Things Manmade
Fly ash ~ 10-20 mm
Atoms of silicon spacing ~tenths of nm
Head of a pin 1-2 mm
Quantum corral of 48 iron atoms on copper surface positioned one at a time with an STM tip
Corral diameter 14 nm
Human hair ~ 60-120 mm wide
Ant ~ 5 mm
Dust mite
200 mm
ATP synthase
~10 nm diameter Nanotube electrode
Carbon nanotube ~1.3 nm diameter
O O
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O OO O OO OO
O
S
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O
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O
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PO
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The Challenge
Fabricate and combine nanoscale building blocks to make useful devices, e.g., a photosynthetic reaction center with integral semiconductor storage.
Mic
row
orl
d
0.1 nm
1 nanometer (nm)
0.01 mm
10 nm
0.1 mm
100 nm
1 micrometer (mm)
0.01 mm
10 mm
0.1 mm
100 mm
1 millimeter (mm)
1 cm
10 mm 10-2 m
10-3 m
10-4 m
10-5 m
10-6 m
10-7 m
10-8 m
10-9 m
10-10 m
Vis
ible
Nan
ow
orl
d
1,000 nanometers = In
frar
ed
U
ltra
vio
let
M
icro
wav
e S
oft
x-r
ay
1,000,000 nanometers =
Zone plate x-ray “lens” Outer ring spacing ~35 nm
The Scale of Things – Nanometers and More
MicroElectroMechanical (MEMS) devices 10 -100 mm wide
Red blood cells Pollen grain
Carbon buckyball
~1 nm diameter
Self-assembled,
Nature-inspired structure
Many 10s of nm
My Personal Early Nanotechnology Motivation
Li LiI
PVP-I CT complex
Li+
20 nm nanorods of MnO2 for positive electrodes
in Li ion batteries
• Quantum Confinement
• One Dimension
• Quantum Confinement
• Three Dimensions
For absorption, energy of photon absorbed goes
as 1/L2, smaller particle absorbs larger
energy photon, who’s wavelength is smaller (toward blue), and longer wavelength photons (toward red)
are transmitted.
Figure 7.2. Solutions of quantum dots of varying size. Note the variation
in color of each solution illustrating the particle size dependence of the
optical absorption for each sample. Note that the smaller particles are in
the red solution (absorbs blue), and that the larger ones are in the blue
(absorbs red).
For light scattering, the photon wavelength must be
smaller than the particle size, and the smaller particles tend to
scatter only the shorter wavelength photons (toward blue)
.Nanomaterials
• C. Dimensionality
• D. Chemical varieties
• E. Shapes
• F. Synthesis
– 1. Lithography
– 2. self-assembly
• Synthesis
1. Lithography
Developing Positive Negative
Etching and Stripping
Polymer Resist
Thin Film Substrate
Resist Resist
Exposing Radiation
Figure 1.1. Schematic of positive and negative resists.
Figure 1.6. Schematic of a focused ion beam system.
1 mm
400 nm
300 nm
200 nm
160 nm
120 nm
100 nm
80 nm
60 nm100 nm
Carbon Nanotubes/Nanocones with Various Catalyst Patterning Dimensions by E-beam Lithography
Figure 2.1. The process of forming a self-assembled monolayer. A
substrate is immersed into a dilute solution of a surface-active
material that adsorbs onto the surface and organizes via a self-
assembly process. The result is a highly ordered and well-packed
molecular monolayer. (Adapted from Ref. 9 by permission of
American Chemical Society.)
.Characterization and Handling
– a. Optical Tweezers
– b. Electromagnetic tweezers
– c. In nanotemplates
– d. Structural Analysis by TEM, SEM, X-ray, etc.
Ballistic Nanotube MOS Transistors (Chen,Hastings)
Wd
D
L
SWNTSWNT
SiO2
Source
Al-Gate
Ti
HfO2
Drain
L
L~20 L~20 nmnm
Placement of Nanotubes by E-Field
(The first-demo) Nanotube Field-Effect Transistor(FET)
E-Beam Lithography
• Measurements
Figure 3.1. Schematic showing all major components of an SPM. In
this example, feedback is used to move the sensor vertically to
maintain a constant signal. Vertical displacement of the sensor is
taken as topographical data
Coarse approach
mechanism
S
c
a
n
n
e
r
Sensor
Sample
Reference
-
Signa l
feedback
data
Figure 3.1. Schematic showing all major
components of an SPM. In this example,
feedback is used to move the sensor
vertically to maintain a constant signa l.
Vertical displacement of the sensor is takenas topograph ical data.
Major equipment
• Focused Ion Beam System (FIB) (scheduled for installation in mid 2007) • Atomic Layer Deposition System (ALD) • Rapid Thermal Processing System (RTP) • Plasma Enhanced Chemical Vapor Deposition System (PECVD) • Standard Resolution Electron Beam Lithography (EBL) • Atomic Force Microscope for Nanopatterning, and Manipulation (AFM) • Atomic Force Microscope for Atomic Resolution Imaging (AFM) • Quartz Crystal Microbalance (QCM) • 4-furnace bank of 3-zone oxidation, dopant diffusion, and annealing furnaces • Class 100 Clean Room • Spin-Coating Station • Photolithography System • Surface Profiler • Chemical Treatment Station (cleaning, etching, and functionalization) • Ion Milling System • Plasma Cleaning/Oxidation System • Gas Cabinet Bank • Experimental Materials Thermal Evaporator • Standard Materials Thermal Evaporator • Electron-Beam Evaporator • Multi-target Sputtering System • Probe Station and Device Characterization System • Four-Point Resistance Measurement System • Ellipsometer • Optical Microscopes • Dicing Saw • Equipment Cooling Systems (3) • Inductive Coupled Plasma (ICP) Etching System (scheduled for installation in Feb. 2006) • Experimental materials sputtering system (scheduled for installation in mid 2006) • Ultra-High Resolution EBL and SEM System
Clean Room
Photolithography
Rapid Thermal
Processing
Quartz MicroBalance
Plasma
Enhanced
Chemical
Vapor
Deposition
Reactive Ion Etching
Atomic
Layer
Deposition
IV. Nanotemplates
• G. Inorganic
• H. Organic
Fig.2 (a) Nanostructure of anodically formed Al2O3 template. (b) its cross-section, (c) catalyst deposited at the bottom of the pores, (e) vertically aligned nanotubes, and (f) TEM
image of a nanotube.
(Chen, Singh, DeLong, Saito, Yang, Bhattacharyya, and Sumanasekeras)
Nano-scale Material Research
(a)
(b)
(c)
Catalyst
200nm200 nm
Vertically aligned MWNTs
embedded in AAO insulator
(d)
Si substrate
SiO2
SiO2
Carbon nanotubes
AlSiO2
Hexagonal Cells
Nano-template
Horizontally
aligned
The first vertically aligned nanotubes on silicon substrates using templates
• Fig. 3 Schematic representing the helix-coil transitions within the pore of a Poly-L-Glutamic Acid functionalized membrane (a) random-coil formation at PH > 5.5 , (b) helix formation at low pH ( <4 ).
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