Progress in the science and application of amorphous materials

Journal of Non-Crystalline Norlh-Holland.

Solids 90 (I 987) 229

242

Amsterdam

PROGRESS

IN THE SCIENCE

STANFORD

R. OVSHINSKY

Energy Conversion 1675 West Maple

AND APPLICATION

Devices, Road, Troy,

Inc. Michigan

OF AMORPHOUS

48084

MATERIALS

U.S.A.

and DAVID

ADLER

Department Massachusetts

of

Electrical Institute

Engineering of Technology,

and

Computer Cambridge,

Science, MA 02139

U.S.A.

Amorphous and disordered materials are becoming the materials of choice in many areas of energy, information, and synthetic materials. In energy, we show how the much-desired goal of high efficiency, stable, and low-cost amorphous photovoltaics has been accomplished. In information, we describe how the crystalline revolution is now reaching its technological limits, and how amorphous devices: ranging from memories and transistors to threedimensional circuits, will become the preferred solution to these problems. In synthetic materials, we show how materials freed from lattice constraints can be engineered for the new requirements of modern industry. All of this has been made possible by the basic scientific understanding of the amorphous state which we will correlate with the technological advances. 1.

INTRODUCTION The way

we work,

materials. for

We

their

passive

everyday on earth

work

as

but

in

was started

that

to atomic

also

to

discovery

be

was

and

its

and

the

electronic

was

not

the

transistor

use

of

revolution, the

giant

a physical

occurrence

order

to

the

but step

not

rather

by is,

that creation

high-density

0022-3093/87/$03.50 0 Elsevier Science Publishers (North-Holland Physics Publishing Division)

B.V.

physics

in

continued

was

many

materials

this the

new

technologies,

integrated

circuits.

When in

or could

an

appreciated

technology. made

we

of

there

was

defects

After of

it

was

dopants,

be controlled. the

of

germanium

hampered

principles

forward

apply

or

that

could

new

the

once

how

and transfer

In a sense,

only

was

both

materials, 1930's.

in only

widespread.

how we encode

in

impurities, current

is,

action

silicon

glasses and

affected

not

as

upon

of

time--not

are

and

transistor

such

deliberate

the

form

ancient

of

controlled

periodicity

then

1947

crystalline

in

an

materials

in that

upon

the

transparency, of

glassy

started

understood

material

impurities,

example,

the

moon,

depends in

inertness, artifacts

intelligence, based

be

periodicity

had

semiconducting form

the

our

civilization, solids

their are

which

originally to

as

They

heavens--on

how we utilize

inevitability

but

the

industrial noncrystalline

such

revolution,

information, which

entire

used

containers.

transistor and

our

long

properties,

use

The

indeed, have

a

crystalline unintentional

be

introduced

development, fueling

it of

the

as,

for

In

the

1950's,

periodicity,

noncrystalline

seemed

on an occasional

to

empirical

Indeed,

noncrystalline

materials

of

solids,

have

no

basis,

such

solids

choice,

since

did

of

as

as

were

they

because

possibilities the

of

the

deemed

seem

to

lack

of

materials

development

automatically not

their

electronic

have

except

Xerox

not

any

drum.

to

be

the

advantages

over

crystals. We

shall

describe

companies are

the

prospecting

in

uninitiated,

who

surprised

fact

is

that

on

amorphous

of

scientific

that

are

now

and

revolution

being

made

is

the

change

most

information,

post-industrial

of

can

now

another;

and

provide

from

the

as they

well

as The

have

local

precisely

this

total

activity

in

interactive

can

provide The

amorphous

the

be

sophisticated

defined

chemical

the

will

technology.

structureless;

materials

importance

that

are

they

characteristic

both products of

such

signal

of

the

a scientific

value. for

application

materials.

revolution,

materials

very

experience,

of

more that

chisel,

production

be

and

However,

applications.

developed

areas

and

and

paradigmic

important

a

can

fundamental to

exists

technological

or

mindset

and

understanding

and

and

one

three

energy,

the

haner

of

from

structural,

diversity, of

far

as more universities

materials.

and

that

discoveries

uniqueness, shifting

are

electronic,

years

tools,

materials

space,

environment

25

place many

amorphous

already

than

taking the

crude

there

environments

three-dimensional

rich

of with

more

is

to join

field

experimental

and

The

new

that

based

that

rushing

prospecting

equipment,

structures

are

this

find

understanding

momentum

world

are

to

analytical

2.

a growing

throughout

These

all

three

of three

are

amorphous

areas

materials

are

currently

in

the

bedrock

are of

crisis.

the

Amorphous

solutions.

ENERGY 2.1

Solar

There

Cells are

stability,

three

and

key

issues

production.

in.

We will

any

solar-cell

review

technology:

how we

have

efficiency,

broken

through

these

barriers. Single-junction silicon

suffer

to

sunlight.

exposure high

PIN

alloys as

efficiencies

10%

devices

severe

rapidly

coupled

manufacturing

process

We

recognized

have

conventional in

Laboratory-scale degrade

irrelevant.

efficiency

using

degradation to The

with

the

form

an the

low

performance

devices 5-6%.

with

hence

relatively

making low

throughput

insurmountable problems

hydrogenated

their

of barrier

associated

value the to with

amorphous after

initial

prolonged

efficiencies claims of

of the

conventional low-cost hydrogenated

as initial

stabilized batch

power

usage. amorphous

silicon the

alloys, problems

and

single-junction development

solar

cells

in

production,

losses

established

in

processor

materials tandem

Using

in

This

device

narrow

band

gap which efficiency.

are

an

and

unique

In

have

order

to

achieve

develop

high

this

quality previously

reported with

on the

development

materials,

light

efficiency

for have

conversion

Although

one-,

two-,

The has

narrow efficiency;

a

1

cm2

gap

new

absorption

splitting

20%

stability

with

based

on

us

to

break

held

back

the

that

device

of

our the

field

band

its gap

for

the

active

area

of

of

single-junction

to 1.5

and

alloy these

and gap

steel

11.3%

and

conversion

triple

12.0X,

same-gap respectively.

devices

multi-junction

which

fluorinated

stainless

an

nt

reported

have devices

similar is

much

devices. our

theoretical a

highWe have

recently

on

Tandem

same-band

stability

a PIN

need

silicon

achieved

11.4%

must

For

layers.

Using

devices

device.

three-cell

using

pt

and

one

intrinsic

loss.g

layer

of

one pt

We have

PIN pt

does

high-quality

optical

efficiencies

Mterials

example,

only

n+ and

of

single-junction

efficiency

approached

not

high-quality

low

structure, devices.

fluorine.l*7*a

entering

the the

tandem

microcrystalline and

and

efficiencies, to

of

a

that

also

a fluorinated

devices

gap

developed

single-junction

development

fabricated

with

conversion

the

conductivity

we have

substrates

but

incorporation of

dark

from

means

material

materials

superior

has

in

materials

necessarily

intrinsic

high

efficiencies

high-quality

configuration,

has

a configuration

technology

which

we have

laboratory.436

improved

allawed

barrier,

alloys, our

spectrum the

and

photovoltaics.

first

on the

for alloys,

amorphous

lightweight

sti-band

manufacturing

process

efficiency-stability-production

excellent

16-inch

manufactured.

successfully

requirement

fluorinated

the

roll-to-roll

amorphous

with

absolute

long,

been

in

have

plant silicon

of

configuration,

We

minimizes solar

layers

produces have

and

amorphous

silicon-germanium

stacked-cell

The

structure,

flexible

and cells

of

research

Sharp-ECD

six

efficiency

materials

in

a lOOO-foot

by

and

stability.

only

The

which

calculator

silicon

fluorinated

properties,

in

coated

addresses

limitations

which

example.

conversion

which

the

structure

fashion of

good

not The

good

is

a triple-junction

conversion tandem

a

continuous

13%

exceedingly

practice,

process

Millions

a record has

offers

is

amorphous

achieved

into tandem

roll

a

material

recognized

degradation.5

roll-to-roll

cells.

also

the

substrate

fluorinated

already

put

reduces

Japan

a

steel

flexible

that

in

employs

silicon

a new fluorinated We have

and

and

1981

stainless

developed

above.'-4

but

recombination

wide

have

described

amorphous limit.

broaden eV

silicon We

the fluorinated

spectral

alloy

have

with

developed response

amorphous

1.7

eV band

proprietary and

increase

silicon-germanium

the

alloy

that

exhibits

absorption made

at

are

of

fluorinated

for

eV fluorinated

three-cell

in

triple,

11.7%

were

the

shows

the

In terms with

initial

hours

of

for

reported of

stability,

of

value

is

the

show

exposure,

as

reported further

increase

successfully

developed

fluorinated

sub-band out to

gap that

obtain

well

the

as

similar are

eV,ll

low slopes

fully

While

there

is

mass

purpose.

As early

designed

and

processors.

deposition dopant concentrations

These

in

Figure

triple

2

device

best

after

10%

2500

stabilized

stability

data

of

continuous

hours

should

be compared

with

in

Fig. 1.5

curves

on

the

50%

and

This intrinsic

of

the

process

a proprietary is

curves

3-6

fluorinated

us

slopes

as

also

have

materials

source developed need

can

provide

of

energy,

to

serve

and

has

amorphous

can

be

compared

process means

pointed

allowed

configurations,

roll-to-roll

roll-to-roll

be

similar

this

the

eV,

practical.

be

recognized

have

1.40 excellent

that

photovoltaics to

of

should

that new

attainable

continuous

ECD designed

It

very

made

amorphous

ECD

gaps

device

are

had

band

obtain We

exhibit

5.

noted

must

eV.

eV materials

have

further

beyond

one

1.5

materials

eV and

generations

Since

have

multi-junction

even

1970's,

efficient

13%, than

As these

that

four

the

Our

that

worldwide

newspapers.

process,

is

technology

as the

contamination.

efficiency

value The

beyond

shown

into

production

This of

This

densities.

question

built

13% cells.

gap

2500

narrower

two

It

defect

20% or

no

date.

These

1.7

pollution-free,

low-cost

printing

as

densities. low

approaching

nondepletable,

and

3.

after

eV.12

2 represent

incorporated

efficiencies

the

13.0%,

12.5X,

initial

Fig.

materials

1.15

13% efficiency.

and

its

to

gap

properties

1 and

defect

dual-band

in

4.

band

and

absorption

curves

a

efficiencies

with

1.25

Fig.

device

materials

eV,

using

of

solar

YOX of

efficiency

in

a

tandem,

others.

high-quality

1.34

shown

achieved in

shown

by

that

retains

highest

two-cell

The

amorphous

the

achieved

fabricated

structures.

shown6

as

no loss

were

that

Using

have

gap

efficiencies

for

fluorinated GuhalO

device.

11.2%

AM1 exposure,

devices

reduction

this

we have

continuous

efficiency

To

respective

value

the by

we

Dual-band

devices

a-Si:Ge:H

effects.

alloy,

quadruple

their

that shown

light-induced

eV materials;

1 plots

and

clear

been

device.

1.7

efficiency

quadruple light

and

characteristic of

is

also

reduced

Figure

a-Si:Ge:F:H,

silicon-germanium

highest

J-V

absorptions.10

It

has

much

four-cell

eV

achieved6

represents

It

a single-junction

and

1.5

a-Si:F:H,

a-Si:Ge:H.

amorphous

fluorinated

gap

for

quality. exhibits

efficiency

sub-band

energy

conventional

higher

material

10.0%

low

versus

ECD and

materials

1.5

very

coefficient

to

best

illustrated

by

layer

obtained

from

is

data

Sharp's

a this since

silicon with

the

a continuous

effectively SIMS

a

minimize on the roll-to-roll

dopant

233

I

Sub-Band Gap Absorption Amorphous SiGe Alloy

for

TRIPLE v,

STRUCTURE

= 2.56 volt

Jw = 7.0 mAlcd FF = 0.72 0.0 f I

Area = l.0cm2 13” = 100 mWlcm2 Pmar = 13.0 mWlcmz I

_J

3.0

FIGURE.1 Absorption coefficient a function of photon energy for a-Si:Ge:F:H and a-Si:Ge:H alloy films compared to that of an a-Si:F:H film with a 0.3eV larger band gap. Also shown is a conventional a-Si:Ge:H curve.

3.0

as *

FIGURE 2 Current-Voltage of a triple-junction efficiency of 13%.

solar

characteristic cell with

TRIPLEDEVICE ,NlTlALEFFICIENCY j/ 112-b

0.0 0

500 1GOo 1500 INDOOR AM1 EXPOSURE

FIGURE 3 Conversion light-soaking time triple device.

for

2cthl 2503 (HOURS)

efficiency a dual-band

vs.

FIGURE 4 Stability of a Sovonics multi-junction solar cell after 2500 hours of continuous exposure compared to recent results on typical single-junction a-Si:H cells.

an

processor boron

built and

intrinsic

by

ECD,

as

reported

phosphorous

concentrations

materials,

indicating

by

Hirobe

were

et

less

the

al.13

than

excellent

They

5 x 1016

found

that

the

in

the

atoms/cc

isolation

between

deposition

regions. The

uniformity

parameter

in

of

the

film

machine.

To

yield

address

density

of

NASA's

Wp/kg,

even

have

Our

more

also

a

the

crucial

uniformity

roll-to-roll

production two-cell

alloys.

Figure of

10 times

As our

tandem

7 illustrates

several

consecutive

the

outdoor

output been

modules

in

performance of

data

our

from

to

design

electrical results that of

excess

space

have

impressive and

nearly

this

figure

that

device

multi-junction

devices.

terms been

can

various

on

shown

also

to of

be

superior

to

accelerated

confirmed

now be

costs

now

to

stress

in

Florida

and

a reality.

are

55 120W

gallons

hour.

and any

For

conductivity.

a pump)

the

with

solid-fuel and

yielding

occupies

water

Thermoelectric

have

system

the 13V,

based

bismuth-tellurium example,

(including

devices are

thermoelectric

thermal

disordered

of

of

devices

maximize

minimizing

design

array

These

to

a voltage

per

portable, to

chosen

lbs.

at

an

power.

modified.

weighs

attendant

of

while we

chemically

1000

marketing

120W

that when

pro&es

completely

maintenance

mass indicate

in

is

1W

obtained

that

of

lightieight,

record

single-junction

power

alloys

are

system 3 ft3

have

conductivity, are

alloys

irrigation

air data

market

Company

delivering

and

we

the

Devices

ability

Excellent

at

incorporated,

independently

solar

Thermoelectric of

weight,

previous are

of than

the

low-cost

Thermoelectric

capable

the

effect

have

Ovonic

unit power

new materials

performance

power

dream

per produces

dramatically.

higher

Our

based

than

more

modules

The

delivered which

deliver

India.

power

power

tandem

testing.16

2.2

of

studied

single-junction

flows

generators

high

reliability

no movable

are and

low

parts.

Batteries

ECD

has

developed

output

as

power

density.

size

also

producing

efficiency

mo&llel4

goal.

Our

devices

2.3

in

is 6 shows

our

currently silicon

consistency

issue

1995

structures.15

in

from

is

web

Figure

obtained

amorphous

ultralight

2,418

go up We

about

web machine

and

the

an

twice

upon

the

the

uniformity.

runs.

developed

will

proouct

fluorinated

excellent

across

deposition

the

production

using

production

the

across

Our

devices the

of ensuring

for

a

conventional load-levelling

rechargeable

NiCd These

but

hydride

with

batteries applications.

only run

battery

half the

with

the gamut

Finally

size, in

size a

the thus

from practical

same

power

twice small

the to

electric

room

235

1

Sub-Bad Gap Optical Absorplion Amorphous Si-G-F-H Pholovollaic

0, Alloys

FIGURE 5 Absorption coefficient*as a function of photon energy for a-Si:Ge:F:H alloy films with various band gaps.

FIGURE 6 of position deposited process.

Film thickness as a function across a strip 35-cm wide, by ECD's continuous web

x Y p

7 -

t:

-

-601 9 . MATERIAL

EFFICIENCY

-40

65 115

for

FIGURE 7 a typical

e

*YIELD - 20 IJIIIII’II. 117

Efficiency set of

119 121 RUN NUMBER

and runs

on

123

125

yield as a function of a roll-to-roll production

0

run

number machine.

automobile for

may

batteries

be

in

will

the

offing.

sharply

It

increase

is

almost

with

the

a certainty

that

growing

the

solar

markets

photovoltaic

technology. Figure 2.4

8 shows Hydrogen

Despite storage

are

hydrides has

its

many

well

known.

with

been

With

of

a potential

developed

fuel,

of

the

of

generation

our

Some of

ECD's

hydrogen density

of

we have

and

of

reversibility.

principles

solved,

new batteries

8

problems high-storage

thermodynamic

application

energy

utilizing

the

lightweight,

lo+temperature

FIGURE

3.

pro&c&.

Storage

as

ECD has

by

problems

energy

Energy

advantages

possible

storage,

ECD's

and

excellent

made

the

energy

several Production

put

This

amorphicity.17

great

emphasis

on

hydrides.

Energy

Products.

INFORMATION The sine

qua

non

transistor. electromechanical integrated

circuit revolution.

information Everyone

turning

into which

undergoing

the

new

in

of is

the

approach technology.18

a

same the

trauma is

The

leading

the as and

crystalline similar technol'ogy

been

the

basic

tubes,

building oil

and The

systems.

been the

crytalline

vacuum

information

has

importance

needed--that This

and

devices,

upon for

other

crisis

same

has

memories,

and

ubiquitous

Valley. depends

same

computer

become

making

society magnetic

However,

Death

industry,

information-based replaced

has

field

field.

A

our

relays

electronic

amorphous

of has

It

block

reached crisis

Silicon

of in

in

Valley

the the

the

energy

is

slowly

electronics

user,

the

computer

technology,

is,

of

course,

reasons. of

large-area is

not

thin-film limited

devices by

the

based size

of

on a

wafer

or

the

constrained

opportunity

memory

has

The

the

dream

of

Although

there on

quite

low,

has

transistor

on

an amorphous

often

become

displays

(LCDs)

are

wide

of

extension

to

in

the

but

the

till

of

color.

flat-screen

proprietary results

color

capability.

in

ECD has

already wide-area

solar-cell

applications,

grey

and

ECD,

solved

the

In However,

to TFTs

quality

by

amorphous-silicon-alloy

ECD diodes

simpler

device

display

and

many

large

and

of

which

shorts the

a special structure,

gate

thin-film in

steps, have

thus

far crossing

The the

led

gate

to bus

alternative TFTs

configuration.lg no

a

including

by

dielectric. replacing

with

for

elements

caused

switching

good

low-temperature

active

processing

areas,

a

(pixel).

materials

of

the

ideal

inexpensively

these

benefit

for

involves in

An

angle,

of

poor

we employ

element

rapidly films

in

angle,

which

wide-viewing

LCD

which

viewing

in

has

existing

amorphous-silicon-alloy ideal

frequent

electrical

displays with

imaging.

each

fringe

calculators,

lines,

color

of

require

over

computer

LCD,

capability

capability position

hand

problem

narrow

contrast,

be

and

matrix

CRTs,

requirements, and

dominant

address

at

major

instabilities,

presented

large major

poor

principle,

photolithography

watches

thin

the

appear

a

The

very

high

power

achieved in

of

Liquid-crystal

demands,

and

active switch

the

with

LCD.

much

device at

demands

lcw

contrast,

low-defect-density

flat-panel

a

as

low

an

speed,

would

poor

has

voltage

multiplexed

in

is

high

(TFTs)

and

poor

power

their

already such

semiconductor

processing.

involves

have

scale,

(< 3OOOC)

solution

been

voltages

developed

alternatives.

low

of

problem

transistors

threshold-voltage

gate

principles,

of

promise.

demonstrated

depositing

high-precision

because

unfulfilled

amorphous

This

TFTs have

relatively

and

television

results

of

fabricating

device

physical

of

market,

displays

this

in

the ITFT).

currents and

how a new

bulkiness

LCDs

requirement

to

requires

towards

resulted

of

drives!

transistor

source-to-drain

availability,

the

loss

solution

disk

computer

effort

possibility

promising

is

visibility,

the

the

an

high-density

of

up

meter

Displays

been

technology

kilometer

opens

cubic

source-drain

new

to

display

concept now

has

It

one

TFT.

most

small-area

of

we describe

grey-scale full

which

thin-film

typical

entirely

realizing

cost,

square

the

for

accustomed

without

lines,

deal

Large-Area-Flat-Screen

We have

low

great

3.2,

mismatches.

in

integrated

This

section

lattice

amorphous

microamperes

based of

3.1

a

XV. In

one

alloys,

approximately

problem

replacing

high-quality

been

of

by

three-dimensionally

a

tens

dimensions structures

amorphous-silicon

performance. a

of

a

of

based

two

three-dimensional

potential

development

of

to

of

by This

dielectric

or

crossing

bus

lines,

requirements. process

that

excellent

overall

has

urn

x

steps,

is

a high-yield,

prodced Figure

processed 20

using This

urn.

and

diode

techniques has

an

devices

with

the

I-V

and

having

an

active

factor

of

n = 1.6

ideality

CURRENT VOLTAGE DEPENDENCE 20 pm x 20 ,m ODS DIODE AWER IS COMPLETED

alignment manufacturing

uniform

9 shows

VLSI

1 wer

low-cost

reprocmcible,

stability.

ECD diode, 20

processing result

already

long-term

typical of

fewer

The

characteristic

of

a

area and

a

OF A TYPICAL PROCESSING

M NE.8 -

Volk

FIGURE 9 Current-Voltage after processing. curve is for reverse

reverse

saturation

factor

is

lo-*A/cm2 area

out of

3.7

on the

impedance The

and

52 lines

a measured

the

3V,

remains

inch,

constant

diode lower

rectification

density per

large-area

20 urn ODS to +3V, the

with

ratio

of

below

an

active

12:l.

flat-screen

It

thus

displays

are

comnerciality.

is The of

MOSFET. operates

holes The

opposed

called the

MOSFETs.

the

device. (as

At current

is

and

of

capabilities of

lD-13A/cm2.

reverse-bias

reliable,

incorporates

DIFET

electrons

inches

20 pm x forward bias

Transistors

and speed

DIFET

7.7

transistor20

and

transistors high

a typical is for

The resolution

threshold

new

transistor)

of

the

economical,

Thin-Film

ECD's

density and

-1%'.

x

finally 3.2

1010, to

that

the

current -

appears

dependence of upper curve to -lOV.

The bias

to

amorphous

bipolar

value

a single

carrier

electric

modulating in

charge MOSFET)

kinds

high

current

the

high

input

the of

is

bipolar

the

1~

to

effect

both

as

double-injection

both a

well very

field of

exhibits as

requires a

of in

DIFET

it

injection

features

devices

amplifying

by application

(double

desirable

Accordingly, by

great

a DIFET

most

power.

current

of

control

gate

charge that

and input

carriers since

both of in

electrons

a

and

holes

charge of

are

charged

applied

to

electrons

is

the

holes,

The new DIFET

the

will

because

conventional

amorphous-silicon-alloy

has

been

about

shown

2000

presence from

to

PA at of

the

it

both

DIFET.

large the field

voltage

product

the

anode-cathode 25V

and

can

result

provide

may be

a visible

limitation by

in

light,

very thin-film

already

a factor In

visible

power

of

15

addition, light

optical low

of

It

10).

modulated only

become

future.

amorphous-silicon-alloy

current Fig.

requiring

near

these

extremely will

transistors.

(see

holes will

on

is

current-carrying effect

of

capability

applications,

An additional

impact

the

and of

and

of

control numbers

result

which

applications,

1~

of

large

conductance The

capability,

computers

very

amount of

amount.

electronics

overcomes

electrons This

conununications

a

flow its

large

switching

increase

a gate

very

high-bit-density

have

transistors

same

the

increasing a

amorphous

in

the

amplify

thereby

faster

present-day

important

polarities, can

by

DIFET's

to

more

opposite electrode

capabilities

important even

gate

and

current-carrying features

in

the

to the

emission output

drive

solid-state

for

signals. laser.

(b) 2000-

jaoo-Anode-Cathode

FIGURE 10 a function

The

Anode-Cathode characteristics of gate voltage.

profound

integration

changes

will

spur

longer

refer

to

quantum

leap

can

generation.

Voltage

in

that computer

fifth-generation be

described

of

the

= 25V

amorphous

now-possible

technology or only

so

sixth-generation a

alloy

DIFET

three-dimensional are

as

silicon

phase

revolutionary

amorphous that

computers. transition

as

we

no

The coming to

the

nth

4.

SYNTHETIC While

MATERIALS

the

conanercial

two

pillars

importance

largest

industries

materials

materials--for

Age.

However,

occurring

depleted

the

The

ltiricious, been

All

but

as

protective

values

temperature,

moisture,

Once place in

we overcame atoms

nature,

in we

engineer possible

previously. active

material

but

structurally transmit

its

ability

to

material

that

magnets. thus

be

However,

ECD

and

mirrors

x-ray

5.

controlled makes

also to

find

attain

the

The

x-rays

and

importance

in

threshold

for

of

the thin the

films

the or

encode,

switch,

active

disordered

example,

utilizing a new magnetic

the

most all

way

as

both

advanced

materials visible diffraction

to

these

their

materials laser,

and light.

x-ray

addition

x-ray

to by

electrically

even

world,

ability

received

developed

for

long-desired

laser

the

only

by almost

In

the

is,

for

same

to

achieved not

not

uses

cost

able

been

that

energy,

absorbed

were

simply

occur

superlattices"). throughout

much

attributes is

is

EC0 has

in

multilayer

their as

synthesize,

For

unit

optically

organic for

never

importance energy

present

are

and

had

superconductivity. per

uses

withstand

store

output

novel

have

included

specific

greater,

materials,

("amorphous

to more

materials

cannot

design

where

needed

that

able be

used

transformations

to

the

known

spectroscopic

eventually mirrors

twice

is

be

materials

which

with

not

etc.

catalysis

to

symmetry

ways

electricity,

synthesize

has It

cannot

present

from

in

i.s,

various

information, range

crystalline

to

if

generate

wood

building

wish.

of

materials

that

where

with

corrosion,

primarily

which

space ability

Of equal,

can

but

as we would

many

devices,

that

materials

the

tailormake,

Bronze

of

other

occurring

passive

cost,

constraints

attained

of

and

have

are

three-dimensional

and

fabricate

and

the

the

dealing use

materials

of

identified

and

widespread

naturally

recently

light

Age, when

like

two

foundation

properties.

which

and

Iron

abrasion

the

been

development

would

until

lav

the

always

tne

resist

these

on

the

and

becoming

limitations the

all

for

and

Age,

technology,

are

built

example,

essentially

science,

have

against

hastened

plastics

are

Stone

up

better

materials such

the

of (they

humankind

industrialists

heat,

investigated

Synthetic solids,

of

and

fuels.

etc.,

already

ages

terms

energy

both

materials--for

more

in

and

bumping

forests

and

future

world),

example,

naturally

materials

the

we keep

withstand

the

information

in

technology.

with

of

are

many should

which

needs

action.

CONCLUSIONS We

technology

have

briefly to

the

sumnarized areas

of

sane energy,

of

the

information,

recent

applications and

synthetic

of

amorphous materials.

However,

space

developments, fibers,

limitations which

optical

preclude

include

tool

memory

It

should

tne

be

basis

are

new

"disorder"

at

from a host

science,

prospered now

imaye

clear for

providing and

memory

photocopiers,

under the of

this of new the

beginning the

amorphous

that

that

technology,

and

benevolent of

a

new

and

of

help jobs.

of freedom,

the

important optical memories,

devices, electronic

materials will

new

tyranny age

electronic

switching

amorphous

other coatings,

disks,

scanners,

industries

of

decorative

systems,

sensors, paper

new

detailing

vi&o

systems,

electron-beam-addressable systems,

our coatings,

will the

world's

The

world

crystalline made

imaging whiteboards. soon

form

economy has lattice.

possible

by lived We

by

the

state.

REFERENCES 1) 2) 3)

4) 5) 6) 7) 8) 9) 10) 11) 12) 13)

14) 15)

16) 17)

18) 19) 20)

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