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Selected Topics in Nanoscience and Nanotechnology

Danny Porath 2002

Administrative issues:

Danny PorathTel: 65-86948,

il.ac.huji.ch@chem.porathmail: -EMonday, 12:00-14:00 (15:00)

Papers reading and presentationResearch proposal – as a final workLecture notes – in my homepage:

http://chem.ch.huji.ac.il/~porath/

References – on the web

Course Syllabus1. General survey of NST (1)2. Selected experimental techniques

a. Scanning electron/transmission microscopy (SEM/TEM) (1)b. Lithography techniques (optical, e-beam, direct) (2)c. Scanning probe microscopy (STM/STS, AFM, EFM …) (2)

3. Single electron tunneling – short theory and examples (2)4. Leading directions in NST:

a. Nanoelectronics (2)b. Nanomechanics (1)c. Nanobiotechnology and nanomedicine (1)

5. Summary and future directions (1)6. Presentation of research proposals….

Links to NSThttp://www.foresight.org/

http://itri.loyola.edu/nanobase/http://www.zyvex.com/nano/

http://www.nano.gov/http://www.aeiveos.com/nanotech/

http://www.the21century.com/nano.htmhttp://www.nanozine.com/

http://seemanlab4.chem.nyu.edu/http://www.matar.ac.il/eureka/newspaper15/dreams.asp

....

Some Books…….1. “Nanotechnology” – M. Ratner & D. Ratner

2. “Nanotechnology” – G. Timp

3. “Understanding Nanotechnology” – Scientific American

4. “Nanoelectronics and Information Technology” – R. Waser

With the help of…….

1. Jim Heath - UCLA2. Jim Hutchbi - SRC3. Yosi Shacam – TAU4. Cees Dekker – Delft5. Yossi Rosenwacks - TAU6. Julio Gomez - UAM7. Joshua Jortner - TAU

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Outline Survey NST:1. Definition and description of the term “Nano”2. Why now? Why interdisciplinary? What is new here?3. NST in Israel and in the world4. Top-bottom vs. Bottom-up approaches5. Some of the “tools” for NST

1. SEM/TEM/SPM – The “eyes” to the nano world2. Lithography – The “hands” in the nano world3. Self-assembly and chemical manipulations

6. Examples of “nano” activitya. Nanoelectronicsb. Nanomechanicsc. Nanobiotechnology and Nanomedicine

7. Future ….. In the end of the course…Maybe

Homework 11. Read the lecture on nanotechnology by R.P. Feynmann, "There's Plenty of

Room at the Bottom": http://www.zyvex.com/nanotech/feynman.htmlDoes it promise too much; is it unphysical by today's technology (2002) compared to the 1959 date when it was delivered? Is Nanotechnology just a continuation of the trend toward miniaturization that began decades ago, or is it something qualitatively different?

2. Read the US Government report: "Nanotechnology: Shaping The World Atom By Atom": http://itri.loyola.edu/nano/IWGN.Public.Brochure/Analyze in the same spirit as assignment 1 above.

Here I am looking for the clever insights that a graduate level student can glean from these articles.

3. Presentations to the class: ~ 10 minutes.

×× 300300

×× 300300

A pictorial definition of NanoA pictorial definition of NanoAphid

× 100

Paramecium × 100

Tina (Weatherby) CarvalhoBio Images by:

× 100

Electronics, circa 1985Electronics, circa 1985

40 nanometers40 nanometers

× 1000

Electronics, circa 2010Electronics, circa 2010

Electronics, circa 1985Electronics, circa 1985

Electronics, circa 2010Electronics, circa 2010

Electronics, circa 2040Electronics, circa 2040

X 100

1 nm diameter 1 nm diameter molecular wires molecular wires

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A scanning tunneling microscope image of a Single-Walled Carbon NanotubeA symbol of the origins of Nanoscience & Nanotechnology

The visionThe classic talk: “There's Plenty of Room at the Bottom”Richard Feynman, December 29, 1959. The annual meeting of the American Physical Society at Caltech

• “Why cannot we write the entire 24 volumes of the Encyclopedia Britannica on the head of a pin?”

• “Biology is not simply writing information; it is doing something about it. A biological system can be exceedingly small.”

• “I want to build a billion tiny factories, models of each other, which are manufacturing simultaneously, drilling holes, stamping parts, and so on.”

The visionThe classic talk: “There's Plenty of Room at the Bottom”: Richard Feynman, December 29, 1959. The annual meeting of the American Physical Society at Caltech

• “Why cannot we write the entire 24 volumes of the Encyclopedia Britannica on the head of a pin?”

• “Biology is not simply writing information; it is doing something about it. A biological system can be exceedingly small.”

• “I want to build a billion tiny factories, models of each other, which are manufacturing simultaneously ,drilling holes, stamping parts, and so on.”

Definition ??? T-B/B-UWorld/Israel ExamplesTools

Vision….(a)1. Nanostructures:

a. Contain a countable number of atoms

b. Suites for atomic level detailed engineering

c. Provide access to realms of quantum behaviorthat is not observed in larger (even 0.1 µm) structures

d. Combine small size, complex organizational patterns, potential for very high packingdensities, strong lateral interactions and high ratios of surface area to volume.

Vision….(b)1. Small => …means not only x1000 smaller but also….

a. High packing density

b. Potential to bring higher speed to information processing

c. Higher areal and volumetric capacity to information storage.

d. Dense packing is also the cause of complex electronic and magnetic interactions between adjacent (and sometimes nonadjacent) structures.

e. The small energetic differences between the various possible nanostructures configurations may be significantly shaped by those interactions.

These complexities also promise access to complex non-linear systems that may exhibit classes of behavior fundamentally different from those of both molecular and micro-scale structures.

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Vision….(c)New established disciplines:

a. Electronics: nanostructures represent the limiting extension of Moore’s law and classical devices to small devices, and they represent a step into quantum devices and fundamentally new processor architectures.

b. Molecular biology: nanostructures are the fundamental machines that drive the cell — histones and proteosomes — and they are components of the mitochondrion, the chloroplast, the ribosome, and the replication and transcription complexes. In catalysis, nanostructures are the templates and pores of zeolites and other vitally important structures.

c. Materials science: the nanometer length scale is the largest one over which a crystal can be made essentially perfect. The ability to precisely control the arrangements of impurities and defects with respect to each other, and the ability to integrate perfect inorganic and organic nanostructures, holds forth the promise of a completely new generation of advanced composites.

…and beyond the nice definitions …What it really is….

…and beyond the nice definitions …What it really is….

So….What are Nanoscience and Nanotechnology?

The ability to observe, measure, predict and construct — on the scale of atoms and moleculesand exploit the novel properties found at that scale.Traditionally, the nanotechnology realm is defined as being between 0.1 and 100 nanometers.

1 nm = 1/1000 µm = 1/1000000 mm.

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Some Observations:Nanoscience and nanotechnology pertain to the synthesis, characterization, exploration, interrogation, exploitation and utilization of nanostructured materials, which are characterized by at least one dimension in the nanometer range.

Such nanostructured systems constitute a bridge between single molecules and infinite bulk systems.

Individual nanostructures involve: clusters, nanoparticles, nanocrystals, quantum dots, nanowires, nanotubes…..

Additional Observations:Collections of nanostructures involve: arrays, assemblies and

superlattices of individual nanostructures.

The chemical and physical properties of nanomaterials can significantly differ from those of the atomic-molecular or the bulk materials of the same chemical composition.

The uniqueness of the structural characteristics, energetics, response, dynamics and chemistry of nanostructures is novel and constitutes the experimental and conceptual background for the novel field of nanoscience.

Suitable control of the properties and response of nanostructures can lead to new devices and technologies.

Nanostructures and their assemblies

Metals, semiconductors,magnetic materials

Radiusseveral nm

3-D superlattices ofnanoparticles

Insulators, semiconductors,

metals, DNA

Thickness1 – 1000 nm

Surfaces and Thin films

Metals, semiconductors,magnetic materials

AreaSeveral nm2 – µm2

2-D Arrays ofNanoparticles

DNADiameter: 5 nmNanobiorods

Carbon, layeredchalcogenides

Diameter1 – 100 nm

Nanotubes

Metals, semiconductors,oxides, sulphides, nitrides

Diameter1 – 100 nm

Nanowires

Membrane proteinRadius5 – 10 nm

NanobiomaterialsPhotosynthetic Reaction

Center

Ceramic OxidesRadius: 1 – 100 nm Other nanoparticles

Insulators,semiconductors,

metals,magnetic materials

Radius1 – 10 nm

ClustersNanocrystals

Quantum Dots

MaterialSizeNanostructureNanostructures and their assemblies

Metals, semiconductors,magnetic materials

Radiusseveral nm

3-D superlattices ofnanoparticles

Insulators, semiconductors,metals, DNA

Thickness1 – 1000 nm

Surfaces and Thin films

Metals, semiconductors,magnetic materials

AreaSeveral nm2 – µm2

2-D Arrays ofNanoparticles

DNADiameter: 5 nmNanobiorods

Carbon, layeredchalcogenides

Diameter1 – 100 nm

Nanotubes

Metals, semiconductors,oxides, sulphides, nitrides

Diameter1 – 100 nm

Nanowires

Membrane proteinRadius5 – 10 nm

NanobiomaterialsPhotosynthetic Reaction Center

Ceramic OxidesRadius: 1 – 100 nm Other nanoparticles

Insulators,semiconductors,

metals,magnetic materials

Radius1 – 10 nm

ClustersNanocrystals

Quantum Dots

MaterialSizeNanostructure

(Schmidt et. al.)

Clusters

TEM of CdSe quantum rods, with average size 25*4 nm.

(Banin et. al.)

Nanoparticles

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TEM of CdSe quantum rods, with average size 25*4 nm.

Membrane ProteinsExamples of Quantum Wires

Nanotube

(Dekker et. al.)The Fullerenes:Nanoscale control

over materials properties

Nobel Prize in Chemistry, 1996

NanotubesDNA

(Cohen et. al.)

3.4 Å

34 Å

Nanoscale Fabrication scheme……For example….

(Eigler et. al.)

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Nano Imprint….

(Mirkin et. al.)

AFM Images of DNA-Based molecules

1.0µm 600nm

400nm 300nm

1.5 µmNano ???Not Yet!!!

Nano!!!

G4-

(Cohen et. al.)

Example of DNA-Nanotube hybrid

(Dekker et. al.)

Nanotube circuits (Cees Science cover)

Why now?

1 m 10 Å: 1,000,000,000

Towards the nano (=10-9) scale - Moore’s law:

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Towards the nano (=10-9) scale - Moore’s law:For example….

(Intel site)

The Fullerenes:Nanoscale control over materials propertiesNobel Prize in Chemistry, 1996

The Scanning Tunneling Microscope: Resolving the atomic worldNobel Prize in Physics, 1988

The Development of Technological Means The Development of Technological Means and Computational Power Sufficient for and Computational Power Sufficient for Visualizing and operating in the NanoVisualizing and operating in the Nano--WorldWorld

Why Interdisciplinary?

Adapted from the Asia-Pacific Economic Cooperation on Nanotechnology (http://www.apectf.nstda.or.th/html/nano.html).

The emergence of the nanometer as a fundamental length The emergence of the nanometer as a fundamental length scale of science, engineering & medicinescale of science, engineering & medicine

Adapted from the –Nanotechnology Magazine: (http://www.nanozine.com/WHATNANO.HTM).

The emergence of the nanometer as a fundamental length The emergence of the nanometer as a fundamental length scale of science, engineering & medicinescale of science, engineering & medicine

Graphite latticeGraphite lattice

ModerateModerate--Sized ProteinSized Protein

21st century technology will arise from an understanding of how to manipulate, control & manufacture at the nanoscale –This means interacting assemblies of molecular & macromolecular-scale components

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Publishing and Patenting in Bioscience/technology and Nanoscience/technology -- The First 10 Years

© 2002 Lynne G. Zucker, Michael R. Darby, James R. Heath, and Evelyn L. Hu

0

2000

4000

6000

0 2 4 6 8 10Number of Years from Base Year

Biotech Publishing Index

Nano Patents (x 10)

Nano Pub. Index

Bio Patents (x 10)

Base year =1973 for Biotech; = 1989 for Nanotech

The Fundamental RealizationNano in Israel

HUJITAUBG

WeizmannTechnion

Industry…

From Israeli sites…

.

לחג-המיטב של אתר הידען

החדשות האחרונות

20.9.2002 למיקרסקופ רובוט אלחוטי פועל מתחת: ננוטכנולוגיה

HP 19.9.2002 הננוטכנוולוגיה דיווחו על התקדמות בתחוםואינטל

8.9.2002 זהירות תמנ ע יצירת בועה- ננוטכנולוגיה

העתיד נראה ק טן 14.8.2002

טכנולוגיה- ננוחברה ישראלית הכריזה על חומר הסיכה היבש הראשון בעולם המבוסס על 10.6.2002

7.6.2002 בעולם ובארץ ה ננוטכנולוגיהמצב: הדבר הגדול הזעיר הבא

2.5.2002 למיקרו מנועים ננומטרייםלהוסיף שרירים

"בקרוב זריקות ללא מחטים" 20.4.2002

2001 התגלית המדעית החשובה ש ל - מחש בים ננו 22.12.2001

עשרה מיליון טרנזיסטורים בתוך ראש סיכה 9.11.2001

פרס נובל בכימיה על פיתוחים מולקולריים 30.9.2001

30.8.2001 פיתחו מעגל משולב ע ל גבי מולקולה בודדת יבממדע ני

חזקות כמו פלדה, עצמות-ננו 11.7.2001

?מה הם יידעו לעשות. רובוטים הראשונים צפויים להופיע בתחילת העשור הבא-הננו 19.6.2001

27.11.2000 ינוע הנאנו,ואף על פי כן

אב ק שואב 2.11.2000

"להביט אל תוך החומר"שיטה חדישה 3.10.2000

ש " ובא" באוני ת-טכנולוגיה מתדפק בד לת -עידן הננו 1.8.2000

12.3.2000 הרבה יותר מידע-אלק טרון אחד

הנשק ה אטומי פרייר על ידו- טכנולוגי נ אנונש ק 1.4.1998

ערוצים זעירים רואים את האור: כותרת 1.4.1998

http://www.hayadan.org.il/

וגיה טכ נול

ננו

–

בועהצ ירת

מנע יירות ת

זה

TAU

Nano in The World

NASA for Example….

(From NASA web site)

• Nanotechnology Program Elements- Nanoelectronics and Computing- Sensors- Structural Materials

Nanoelectronics and Computing Sensors

Structural Materials

•Molecular electronics & photonics•Computing architecture•Assembly

•Life detection•Crew health & safety•Vehicle health

•Composites•Multifunctional materials•Self healing

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• Onboard computing systems for future autonomous intelligent vehicles

- powerful, compact, low power consumption, radiation hard

• High performance computing (Tera- and Peta-flops) - processing satellite data- integrated space vehicle engineering- climate modeling

• Revolutionary computing technologies• Smart, compact sensors, ultrasmall probes• Advanced miniaturization of all systems• Microspacecraft• 'Thinking' spacecraft• Micro-, nano-rovers for planetary exploration• Novel materials for future spacecraft

Materials

Electronics/computing

Sensors, s/c components

• Single-walled nanotube fibers

• Low-Power CNT electronic components

• In-space nanoprobes

• Nanotube composites

• Molecular computing/data storage

• Nano flight system components

• Integral thermal/shape control

• Fault/radiation tolerant electronics

• Quantum navigation sensors

• Smart “skin” materials

• Nano electronic “brain” for space Exploration

• Integrated nanosensorsystems

• Biomimeticmaterial systems

• Biological computing

• NEMS flight systems @ 1 µW

2002 2004 2006 2011 2016

NASA Nanotechnology Roadmap

>

Increasing levels of system design and integration

C A P A B I L I T Y

High StrengthMaterials(>10 GPa)

High StrengthMaterials(>10 GPa)

Reusable Launch Vehicle (20% less mass, 20% less noise)

Reusable Launch Vehicle (20% less mass, 20% less noise)

Revolutionary Aircraft Concepts (30% less mass, 20% less emission, 25% increased range)

Revolutionary Aircraft Concepts (30% less mass, 20% less emission, 25% increased range)

Autonomous Spacecraft (40% less mass)

Autonomous Spacecraft (40% less mass)

Adaptive Self-Repairing Space Missions

Adaptive Self-Repairing Space Missions

Multi-Functional MaterialsMulti-Functional Materials

Bio-Inspired Materialsand ProcessesBio-Inspired Materialsand Processes

2002 2005 2010 2015

Biomimetic,radiation resistant

molecular computing

Nanoelectronics and Computing RoadmapImpact on Space Transportation, Space Science and Earth Science

CNT Devices

Biological Molecules

Ultra high density storage

Mis

sion

Com

plex

ity

Compute Capacity

RLV

hνe-

Nano-electroniccomponents

Europa Sub

Robot Colony

Sensor Web

Nanosensor RoadmapImpact on Space Transportation, HEDS, Space Science and Astrobiology

2002 2005 2015

Mis

sion

Com

plex

ity

Sensor Capacity1999

DSI RAX

2003ISPP

Missions too earlyfor nanotechnology impact

Biosensors

Spacestation

Europa Sub

Mars Robot Colony

Sensor Web2020

Nanotube VibrationSensor for Propulsion

Diagnostics

Optical Sensorsfor Synthetic

Vision

Nanopore for in situbiomark-sensor

Multi-sensorArrays (Chemical,

optical and bio)

2010

Sharp CJV

2002 2005 2010 2015

NANOTUBE COMPOSITES

MULTIFUNCTIONAL MATERIALS

SO3

- SO3

SO 3- -H

+ H +H +

SO3-

SO3-

Ca++

SO3-

SO3-Ca++

SO3-

SO3-Ca++

Ca++

Tacky

Non-tackytemperature

SELF-HEALING MATERIALS

Nano-Materials RoadmapImpact on Space Transportation, Space Science and HEDS

SELF-ASSEMBLING MATERIALS

Generation 3 RLVHEDS Habitats

Nanotextiles

Mis

sion

Com

plex

ity

Strong Smart Structures

RLV Cryo Tanks

Production ofsingle CNT

CNT Tethers

CNT = Carbon Nanotubes

2002 2010 2020 2030

Biomimetics and Bio-inspired SystemsImpact on Space Transportation, Space Science and Earth Science

Mis

sion

Com

plex

ity

Biological Mimicking

Embryonics

Extremophiles

DNA Computing

Brain-like computing

Self Assembled Array

Artificial nanoporehigh resolution

Mars in situlife detector

Sensor Web

Biological nanoporelow resolution

Skin and Bone

Self healing structureand thermal protection

systems

Biologically inspired aero-space systems

Space Transportation

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Nano in The world

(Scientific American, September 2001)

Quantum Information ScienceQuantum Information Science Nanoscale MaterialsNanoscale Materials

Biology & HealthcareBiology & Healthcare

Molecular ElectronicsMolecular Electronics

Micro and Nano technologies - status• Micro technologies• 1/1,000,000 of a meter• Devices dimensions

today in the Microelectronics industry ~0.13 µm

• The dimensions will reach 0.1 µm in 2010

• ~1000 million devices on a chip

• Nano technologies• 1/1,000,000,000 of a

meter• 1000 Billion devices

on a chip• Atomic scale devices• Not in

production……... yet.

There are two ways to build a house…...

TopTop--downdown

BottomBottom--upup

The Top-down Approach…

The Bottom-up Approach…

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Main Tools for Nano:

1. Observation:a) SEM/TEM (optical)b) SPM

2. Construction:a) E-beam/optical Lithographyb) SPM Lithographyc) Self assemblyd) Chemistry

Scanning Electron Microscope (SEM) Principle

Radiolarian (in Plankton) x 750

Scanning Electron Microscope (SEM) Principle

(From IOWA U. web site)

SEM Image (Leo 1530)

High resolution image of a frozen, hydrated yeast uncoated chromite

SEM Imaging

~4 nm gap

Before Au55trapping

After Au55trapping

2 nm

Transmission Electron Microscope (TEM) Image (Leo 922 OMEGA)

Si[110] taken on LEO 922 Lattic spacings: [111] = 0.31nm, [200] = 0.27nm

Tunnelling device on the basis of a Si/Ge heterostructure

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Scanning Tunneling Microscope (STM)

Sample

Piezo

Electronics(Current+Feedback)

Computer(Control)

Matrix ofheights(Image)

Tip

I(V) ~ Ve-(ks)

Tunneling between a sharp tip and conducting surface.Piezo enables xy and z movement.Working mode: constant current.The feedback voltage Vz(x,y) is translated to height (topographic) information.

STM Head

דגם

בידוד

בסיס

STM - ראש ה

חוד

בורגמיקרו-מטרי

גבישפייזו-אלקטרי

רכיבי היחידה המרכזית

STM Images

Graphite – atomic resolution: Supercoiled DNA

Atomic Force Microscope ( AFM) Principle

AFM HeadVibration isolation + Stiffness

1cm

Laser diodeWindow for

optical microscope

PhotodiodeCoarse

approach

Piezoelectric scanner

Photodiode adjustment

system

AFM Images

Magnetic bits of a zip disk G4-DNA

100nm10µm

DNA-NanotubeNanotube between

electrodes

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Directions of development in Nano:

1. Nanoelectronics2. Nano-mechanics (MEMS/NEMS)3. Nano-bio(techno)logy4. Nano-medicine

APPLICATIONS: NANODEVICES, NANOELECTRONICS, AND NANOSENSORS

Current Scientific Advances:1. The discovery and the controlled preparation of carbon

nanotubes and their use to fabricate individual electronic devices.

2. The ability to place engineered individual molecules onto electrical contacts and measure electrical transport through them.

3. The availability of proximal probe techniques and their use to manipulate matter and fabricate nanostructures.

APPLICATIONS: NANODEVICES, NANOELECTRONICS, AND NANOSENSORS

4. The development of chemical synthetic methods to prepare nanocrystals and monolayers, and methods to further assemble them into larger organized structures.

5. The introduction of biomolecules and supermolecularstructures into the field of nanodevices.

6. The isolation of biological motors, and their incorporation into non-biological environments.

The Electrical Conductivity of a Single Molecule

(Reed et al. 1997)

Organic Nanostructures: The Electrical Conductivity of a Single Molecule (break-junctions)

(Reed et al. 1997)

Organic Nanostructures: The Electrical Conductivity of a Single Molecule (break-junctions)

(Reed et al. 1997)

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1. The size reduction of electronic devices to the molecular scale will dictate the use of a new physics, because current microelectronics is classical and nanoelectronics is quantum mechanical.

2. The cost of building the factories for fabricating electronic devices, or fabs, is increasing at a rate that is much larger than the market for electronics; therefore, much less expensive manufacturing process will need to be invented.

3. Molecular electronics: molecules, that are quantum electronic devices, are designed and synthesized using batch processesof chemistry and then assembled into useful circuits through the processes of self-organization and self-alignment.

Molecular Electronics Themes4. If molecular electronics achieves the ultimate goal of using

individual molecules as switches and carbon nanotubes as the wires in circuits, we can anticipate nonvolatile memories with one million times the bit area density of today’s DRAMsand power efficiency one billion times better than conventional CMOS circuitry.

5. Such memories would be so large and power-efficient that they could change the way in which computation is performed from using processors to calculate on the fly to simply looking up the answer in huge tables.

6. A major limitation of any such process is that chemically fabricated and assembled systems will necessarily contain defective components and connections. This limitation was addressed in a 1998 paper entitled “A Defect-Tolerant Computer Architecture: Opportunities for Nanotechnology”. (Heath et al.1998).

Molecular Electronics Themes

(Heath et al. 1998)Molecular Electronics

(Avouris et al. IBM)

A Field-Effect Transistor Made from a Single-Wall Carbon Nanotube

(Avouris et al. IBM)

Carbon Nanotube Manipulation

AFM Scanning

Lowering the tip and pushing

VDW forces hold the CNT

(Avouris et al. IBM)AFM Oxidation

61 % Humidity 14 % Humidity

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(Avouris et al. IBM)Theory of CNTTwisting angle

effect on energy band-gap

Bending effect of on CNT Electronic Structure

The NASA Avionic Roadmap1. NASA has created the Deep Space Systems Technology

Program, known as X2000.

2. Every 2-3 years starting in 2000, the program will develop and deliver advanced spacecraft systems and to missions in different areas of the solar system and beyond.

3. In order to achieve reduction in the size of spacecraft, the avionics systems of the spacecraft are being reduced in size with each delivery of X2000, in part by means of integrating nanotechnology with microtechnology.

4. The figure attempts to chart the forecasts of the mass, volume, and power of future avionics systems of spacecraft. The leftmost column shows the Mars Pathfinder spacecraft, which represents the current state of the art.

(NASA)

Avionic RoadmapIntegrated Nanotechnology in Microsystems

Control of mechanical, electrical, optical, and chemical properties at the nanoscale will enable significant improvements in integrated microsystems.

1. When certain materials systems are exposed to a magnetic field, their electrical resistance changes. This effect - the magnetoresistive effect, is useful for sensing magnetic fields such as those in the magnetic bits of data stored on a computer hard drive.

2. In 1988, the giant magnetoresistance effect (GMR) was discovered in layers of nanometer-thick magnetic and nonmagnetic films.

3. a spin valve, could sense very small magnetic fields. This opened the door for the use of GMR in the read-heads of magnetic disk drives.

4. In the spin valve GMR head, the copper spacer layer is about 2 nm thick, and the cobalt GMR pinned layer is about 2.5 nm thick. The thickness of these layers must be controlled with atomic precision.

A Commercial IBM Giant MagnetoresistanceRead Head

A Commercial IBM Giant MagnetoresistanceRead Head

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Additional Nanoelectronic devices…device and architecture options for high-performance electronics

Resonant Tunneling Devices in Nanoelectronics

1. The crucial technology for advancing these quantum devices has been epitaxial growth and process control at the nanoscale.

2. The resonant tunneling diode (RTD) consists of an emitter and collector regions, and a double-tunnel barrier structure that contains a quantum well, as shown in the energy band diagrams.

3. This quantum well is so narrow (5-10 nm) that it can only contain a single so-called “resonant”energy level.

Resonant Tunneling Devices in Nanoelectronics

4 bit 2 GHz analog-to-digital converter, 3 GHz (40 dB spur-free dynamic range) clocked quantizer, 3 GHz sample and hold (55 dB linearity), clock circuits, shift registers, and ultralow power SRAM (50 nW/bit)

(Seabaugh 1998)

The Future of NST ????

Hmmmmm….

In the end of the course!!! (Maybe)