Griscom Stookey Lecture_LinkedIn

David L. Griscom
Naval Research Laboratory, Washington, DC (retired)
impactGlass research international, San Carlos, Sonora, México
2016 Stookey Lecture of Discovery
2016 Glass and Optical Materials Division Annual Meeting, May 23, 2016
Madison, Wisconsin
[Abridged]
The Life and Unexpected Discoveries
of an Intrepid Glass Scientist

STH History: How I became an MOS guru part 1 (mistaken!)
"Diffusion of radiolytic molecular hydrogen as a mechanism for the post-irradiation buildup of
interface states in SiO2-on-Si structures," D.L. Griscom, J. Appl. Phys. 58 (1985) 2524-2533.
When I finally realized my errors, I decided to write a paper that
would pull together all of the most important publications bearing on
the different parts of this highly complex subject and explain how
they all come together.
This 1985 publication was seminal, and constructive, but it turned
out to be far from correct. Nevertheless, the number of citations it
has garnered to date is a phenomenal 372!
Note that MOS stands for Metal-Oxide-Semiconductor, but the metal affects nothing.
The result appears in the next slide.

Here is my Introduction:
A detailed microscopic model for radiation-induced interface state formation in Si-based
MOS structures has long been the holy grail of researchers in the field. The experimental
data upon which such models have been founded comprise electrical measurements on
capacitor and transistor structures and various forms of spectroscopy. The most structure-
sensitive experimental technique has been electron spin resonance (ESR), albeit that the
method is restricted to those defect states which are paramagnetic. The key to securing
the grail appears to lie in refinement and integration of the ESR and electrical results.
68
cites
Before I expose my gross mistake and how the truth of the matter finally evolved, I
want to mention the names of Nelson Saks, Dennis Brown, and Keith Brower as
my sources of electrical results. Without them I could never have reached this point.
5.5 times fewer than
my erroneous original.
STH History: How I became an MOS guru part 2, the plot thickens
D. L. Griscom: Hydrogen model for radiation-induced interface states in SiO2-on-Si structures:
A review of the evidence, J. Electron. Mat. 21 (1992) 763-767

STH History: How I became an MOS guru part 3 (My crapy model)
Griscom, Brown, and Saks, in: The Physics and Chemistry of SiO2 and the Si-SiO2 Interface,
Plenum, New York, 1988, p. 287
My 1985 Model:
Initial results of
γ Irradiation:
OH preexisting in the oxide layer is fissioned by exciton decay:
Bias-Independent
hydrogen drifts toward
the interface as H2

What is an STH?
Thus, my 1988 Model Became as Follows…
STH History: How I became an MOS guru part 4 (STHs at last1)
D. L. Griscom: Hydrogen model for radiation-induced interface states in SiO2-on-Si structures:
A review of the evidence, J. Electron. Mat. 21 (1992) 763-767
Initial results of
γ Irradiation:
1 %
99 % Protons drift to the
interface under
non-negative bias.
It stands for “Self Trapped Hole.” I will tell you about STHs next!
?

To the left is the most important of
the three figures found in the above
paper.
However, I was disappointed with
my overall simulation [dashed curve
in (a)] and planned to improve it. But
other matters intervened
Thereafter I resolved to do further
research and write up a complete
paper chocked full of STH history
and technical details to be ready
to publish in the Riga conference
proceedings.
169
cites
It clearly separates STH1
from STH2.
…that is
until I received the notice at the right:
My first claim to have discovered the STHs

(a) STH1
(b) STHmixed (finally recognized)
(c) STH2
Component Simulations g-Value
Distributions
STH History: Detailed Analysis of ESR Spectrum: g Values
D.L. Griscom, J. Non-Cryst. Solids 149 (1992) 137
Weighted Sum of
the Three Components
Now Used to Fit Experiment
(Mostly STH2) But this peak
is entirely
STH1

STH History: Detailed Analysis of the ESR Spectrum
The yellow box
identifies E′ Centers
*
*
*
*Asterisks identify
features due to
Peroxy Radicals
The red curve is my Physics-Based
Computer Simulation of the STHs
(+ E′ Centers)
*
Here is my best spectrum of a High-Purity
Oxygen-Excess sample of Suprasil W
silica following X irradiation a 77 K

STH History: Detailed Analysis of ESR Spectrum: Models
STH1
STH2
 Hole occupies a non-bonding
2p orbital on a single bridging
oxygen.
 Hole must rapidly tunnel between
two equivalent bridging oxygens
belonging to the same tetrahedron.
 This is the expected structure
for the “small polaron”.
 This structure was not expected.
However, later on, my ESR
discoveries were matched by
ab initio calculations by others.


(a) STH1
(b) STHmixed
(c) STH2
STH History: g-Matrix Analyses: STH1
STH1 Model Empirical g Value
Distributions are
Skew-Symmetric
But Their
Corresponding
Density of States
Are All Gaussians λ is the spin-orbit coupling constant for O-
ion.
g1g2g3
g1g2g3
STHmixed
g value of
free electron
Top of
Valence
Band

STH History: g-Matrix Analyses: STH2
g3 g2 g1
E
∆
σ
Empirical Result:
I derived these equations:
σ
Much deeper in
the valence
band: ⇓
E
STH2
Model
Tetrahedral within experimental error!
Range II order ?

This result blows my mind!!!
Density of States →
Energy(eV)
Pantelides & Harrison
(1979)
Upper Valence Band
Lower Valence Band
STH1 & STHmixed CalculatedSTH2
STH History: Detailed Analysis of ESR Spectrum:
Density of States Derived from g-value Distributions
Here all of my skew-symmetric ESR graphs are converted to energy level
Gaussians, and we are about to compare my experimental data with theory!
100
100
cites

STH History: Conclusions
I wrote it up. But was anyone going to believe me?
8 days before this same
manuscript was received
by the Journal of Non-
Crystalline Solids

Material Measured
Form Property
Fibers Optical
Bulk Glass ESR
Thin Film ESR
Thin Film Electrical
Charge
1970 1980 1990 2000
Date (A.D.)
Amosov et al., Leningrad Griscom, Washington
Chernov et al., Moscow
Griscom, Washington
Brower, Albuquerque
Harari et al., Princeton Saks et al., Washington
*
*
*
*
Nagasawa et al., Tokyo
Sasajima & Tanimura, Osaka
Observed Effects Unexplained STHs Explain All
Many helpers, but I was the
only one to put it all together.
4 times I appealed
for futher funding,
all denied

Here is a Notable 2006 Paper of Mine that I Have Insufficient Time to Discuss
It’s Fig. 2 explains the preceding diagram in further detail.
Apropos of the military/industrial incompetence…
Section 5 relates the story of how I solved the problem of AlliedSignal
ring-laser gyros suddenly failing in orbit in after just one year
100
57
cites
…whereas they had previously operated for 20 years in orbit!

This is a Another Notable Paper of Mine that I Have Insufficient Time to Discuss
While still at NRL I talked Bill Weber into sending me small amounts of each of
his three then-17-year-old nuclear-waste-glass simulants having differing
amounts of 238
Pu. I took copious ESR spectra before leaving NRL…
100
6
cites
15 pages &
15 figures
I think my results are well worth my trouble.
2011
But I only got around to analyzing those data until 10 years later!
But only…
Well it was pretty esoteric.

Yet a Another Notable Paper of Mine that I Have Insufficient Time to Discuss
2011
I began this undertaking with the objective of reconciling certain differences
among three of the brightest materials scientists I’ve ever known.
(all from the former Soviet Union)
However,13 pages later I found myself tearing apart my own model for the role of
chlorine in high-Cl silica glass upon irradiation, published by me and
Joe Friebele in Phys. Rev. B in 1986.
I’m still not certain whether or not I helped significantly in that objective.
17400
74
cites
My bad. But better 30 years late than than not a all!
18 pages

γ irradiations carried out
in the NRL pool facility.
My version of Charles Askins’ original model, which was
lost during NRL’s Optical Sciences Division move to it’s
new buildings.
The great advantage of this rig was that it can measure
induced attenuation at times as short as 1 second,
surprisingly revealing enormous bands at the start …as
compared with a concomitant study in Russia, arranged
by Konstatnin using monochromators, which caused his
group to be unable to record the first hour or so of data.
STH History: Optical Bands (ESR Put Aside)
Growth and Disappearance of 660- and 760-nm Bands in Fibers
γ and fission-reactor radiation effects on visible range transparency of
aluminum-jacketed, all silica optical fibers
D.L. Griscom, J. Appl. Phys. 80 (1996) 2142-2155
My system simultaneously measured radiation-induced
optical bands in four aluminum-clad silica-core fibers,
three of them differing mainly in OH and Cl contents of
the cores. The fourth one was made especially for me by
Konstantin Golant in Russia, thanks to Hideo Hosono
furnishing the F-doped core rod. This was likely NRL’s
first buy from the former Soviet Union.

STH History: Optical Bands Created by γ Rays
Growth and Disappearance of 660- and 760-nm Bands in Fibers
During Iradiation
D.L. Griscom, Appl. Phys. Lett. 71 (1997) 175
High-purity, low-OH,
low-Cl, pure-silica-core
fiber (KS-4V) under γ
irradiation at 1.0 Gy/s
Next we’ll take a closer
look at spectrum #2.

1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0
0
5000
10000
15000
InducedLoss(dB/km)
Photon Energy (eV)
660- and 760-nm Bands in Optical Fibers Appear to Be Due to STH2
760
nm
660
nm
Could these
be STH’s?
Do you remember the red line at
2.0 eV passing horizontally through
the STH2 energy peak back 7 slides
ago?
So now let us now erect verticals
corresponding the horizontal
peaks of STHmixed and STH1.
The orange horizontals of 7 slides ago came with the caution that the eV scale was based on an unknown
parameter close to 1 …so I took it to be exactly 1. So the difference between the position of the red
vertical passing through 2.0 eV and the high point of my spectrum may prove to be the needed
STHmixedSTH1 STH2 Photon Energy (eV)
InducedLoss(dB/km)
Well, here is a red line vertical
to an optical spectrum also in eVs
which corresponds to STH2.
Clearly STHmixed doesn’t
match an optical peak.
And likely neither does
STH1, given no hint
a band tail.
Ergo, this
spectrum must
be solely due
to STH2!

Radiation-Induced “Reconfiguration” of High-Purity a-SiO2 Fibers
t-1
So it appears that pure-
silica-core fibers
are “reconfigured” by
long-term, low-dose-rate
irradiation in such a way
that color centers (now
recognized as STHs)
are no longer formed,
even when the
irradiation continues.
Indeed, a re-irradiation
3 months later peaked
where the original left
off …before once again
heading downward.
I have patented this.
Loss at 760 nm vs γ irradiation time at 1 Gy/s

10
3
10
4
10
5
10
6
10
7
10
8
0.01
0.1
1
10
100
1000
Classical Kinetic Solutions:
Red Curves: 2
nd
-Order; Small Circles: 1
st
-Order
340 rad/s
17 rad/s
0.45 rad/s
Experimental Data:
17 rad/s
0.45 rad/s
340 rad/s
InducedLoss(dB/km)
Dose (rad)
Slope = 1.0
These
Data
Cannot Be Fit by
These Solutions
Note Overlapping Linears
Fractal kinetics of radiation-induced point-defect formation in amorphous
insulators: Application to color centers in silica-based optical fibers
D.L. Griscom, PHYSICAL REVIEW B, Vol. 64, 174201 (2001)

What to do? Well, it was about time to try fractal kinetics.
Fortunately, a Russian colleague of mine, Vladimir Mashkov, had done such a
classical-to-fractal problem of this nature, so I decided to follow his lead. However,
it turned out that my problem was quite different from his…
However, not a one of my many fractal-kinetics articles treated this kind of problem.

My Foray into Fractal Kinetics
D.L. Griscom, Physical Review B, Vol. 64, 174201
Vladimir was looking at E´ centers in bulk, low-OH silica, whereas I was primarily
studying optical fibers, with Ge-doped silica cores.
Nevertheless, after a week of cut-and-try efforts I finally arrived at the following results:
IMPORTANT:
In the present case (Ge-doped silica), there
were dose-rate effects determined empirically,
requiring modification of fractal parameters K and R.
And the Ge(1) and Ge(2) centers
are as different from E´ centers as night is to day!

1000 10000 100000 1000000
0.1
1
10
100
C
B
0.011 rad/s
β=1.017 rad/s
β=0.66
0.45 rad/s
β=0.85
340 rad/s
β=0.52
InducedLoss(dB/km)
Dose (rad)
1th
- and 2nd
-Order Fractal Kinetics of Irradiated Ge-Doped Silica Fibers
My Final Fit for Single-Mode Fibers
A
A
A
A
Solid curves “A” represent
growth and thermal decay of
induced optical of attenuation
at 1300 nm in Corning SM Ge-
doped silica fibers subjected to
γ irradiation at the noted dose
rates. These curves and the
black squares were taken by
Joe Friebele and his helpers.
My small-circles fitting Joe’s
“A” data are derived from 2nd
-
order fractal-kinetic growth
curves applied to Ge-doped
silica glass, but including the
“B” and “C” permanent damage
curves, which I co-optimized by
my cut-and-try procedures.
The gray arrows emphasize
the unidirectional variation
of β with increasingly lower
dose rates.

My Foray into Fractal Kinetics: The Most Important Result
1E-3 0.01 0.1 1 10 100
10
100
(c)
Slope = β
Slope = β/2
SaturationLoss(dB/km)
Dose Rate (rad/s)
1E-3 0.01 0.1 1 10 100
10
-8
10
-7
10
-6
10
-5
10
-4
10
-3
Linear!!!
(b)
Classical 1st-Order Kinetics
Classical 2nd-Order
Kinetics
RateCoefficient(s-1
)
1E-3 0.01 0.1 1 10 100
0.7
0.8
0.9
(a)
Stretched 2nd Order Kinetics
Stretched 1st-Order Kinetics
Power-LawExponentβ
1E-3 0.01 0.1 1 10 100
1
10
100
(c)
Slope = β
Slope = β/2
SaturationLoss(dB/km)
Dose Rate (rad/s)
1E-3 0.01 0.1 1 10 100
10
-9
10
-8
10
-7
10
-6
10
-5
10
-4
10
-3
Linear
(b)
RateCoefficient(s-1
)
1E-3 0.01 0.1 1 10 100
0.6
0.7
0.8
0.9
1.0
(a)
Power-LawExponentβ
Two different ways to normalize the results
Not much difference at all in this
case
2nd
-Order Fractal Kinetics 2nd
-Order Fractal Kinetics
β
k
Nsat
Can Be
Extrapolated!
Two different ways to normalize the results
5 ½ Orders of
Magnitude!
What an Unexpected Discovery this One Was!!!

Joe Friebele and I were co-authors of a
chapter entitled “Color Centers In Glass
Optical Fiber Waveguides,”
1986
which
included the 3 Ge-related features to the
right.
This was the first and only study of it’s
kind making use of both ESR and Optical
methods from 77 K to ~1000 K and a
Bulk sample instead of an Optical fiber.
Ge(1)
Ge(2)
GLPC
ESR: Trapped
Electrons
Optical:
Ge-Lone
Pair Center

And 26 years later I realized that the
story of irradiation effects in Ge-doped
silica glasses was far from understood.
But Joe and I had both lost our notes,
so I had to start over from scratch…
Joe’s optical spectra
were impeccable. So
no problem here.
The big problem was the center one.
Single
Hole
STHs Note the generic
name OHC ca. 1986
Note that by 1992 they
become Self Trapped Holes

The ESR-silent GLPCs rise at 50%
of the combined electrons’ diving.
Ergo, the GLPCs are trapping
electrons in pairs!
Ge(2)
Ge(1) & Ge(2), both
trapped electrons,
are diving↓
What I had failed
to notice were the
consequences of
the STHs trapping
holes in pairs.
STHs
← Over here normal STHs that trap single
holes have disappeared below 200 K, whereas
the real action is from 200 to 380 K. Thus, if each STH
were to trap a second hole (making it ESR-silent) they
may exactly balance the electron pairs of the GLPCs!
Then, both
would follow
the green
arrow!!!

View of a portion of
the crystal structure
of α quartz looking
down a c-axis
channel. The central
circles 1, 2, and 3
are normal silicons.
This one is “Crystal-
like" because it
follows α quartz
symmetry.
These can be called “Glass-like”
“The dynamic interchange and relationship between germanium centers in α quartz”
Isoya, Weil & Claridge, J. Chem. Physics(11), 4876-4884 (1987)
Now suppose
that this Si2+
is replaced by
a Ge2+
…
In that event, Isoya et al. have proven that
an electron trapped at a site occupied by
a Ge2+
has two different options:
(1) Be trapped in a p orbital parallel
to the ɑ1 axis denoted II1 or…
(2) one of the two I1 orbitals.
These can be called “Glass-like”
All other noted details
in black pertain to any
Ge2+
that may take
the place of a
normal Si2+
.

(a) α Quartz (b) GeO2-SiO2 Glass
Twofold
axisof
crystalsym
m
etry
Quasi-twofold
axisoflocal
sym
m
etry
Ground
States
Ge(II)
Ge(1)
∆
Ge(I) Ge(2)
As proven by John
Weil and coworkers
As proven
by me
Ge-Doped α Quartz Ge-Doped Silica Glass
Doubly DegenerateEnergy Wells
Conclusion: The Ge(1, 2) defects in Ge-doped silica glass are two energetically
different configurations of the same defect, as proven to be true
for the Ge(I, II) centers in α quartz …only with their ground states reversed.
Glass-Like
Quartz-Like

My master paper on the natures of radiation-induced point
defects in Ge2-SiO2 glasses
28
cites

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