___________________________________________ group meeting, feb. 2003...
Post on 21-Dec-2015
221 views
TRANSCRIPT
___________________________________________Group meeting, Feb. 2003_____________________________________________
Manuel ForcalesManuel Forcales
OPTICAL MEMORY EFFECT OPTICAL MEMORY EFFECT IN Si:ErIN Si:Er
___________________________________________Group meeting, Feb. 2003_____________________________________________
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
Free Electron Laser facility for Infrared eXperiments (FELIX)
&
AcknowledgementsGroup members from the Van der Waals–Zeeman Institute (WZI):Group members from the Van der Waals–Zeeman Institute (WZI):
M. A. J. Klik , N.Q. Vinh, Dr. M. Wojdak andM. A. J. Klik , N.Q. Vinh, Dr. M. Wojdak and
Dr. T. GregorkiewiczDr. T. Gregorkiewicz
FOM Institute “Rijnhuizen” (FEL Facility) staff members:FOM Institute “Rijnhuizen” (FEL Facility) staff members:
Dr. I. Bradley, Dr. J-P.R. WellsDr. I. Bradley, Dr. J-P.R. Wells
Samples kindly provided by:Samples kindly provided by:
Dr. A. Polman, AMOLF, The NetherlandsDr. A. Polman, AMOLF, The Netherlands
Dr. Widdershoven, PRL, The NetherlandsDr. Widdershoven, PRL, The Netherlands
Dr. F. Priolo, IMETEM, ItalyDr. F. Priolo, IMETEM, Italy
Dr. W. Jantsch, University of Linz, AustriaDr. W. Jantsch, University of Linz, Austria
Dr. J. Michel, MIT, USADr. J. Michel, MIT, USA
Financial support (thank$):Financial support (thank$):
ARL-ERO, NWO, FOMARL-ERO, NWO, FOM
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
Outline
Motivations
Photoluminescence (PL) experiments
Results
Conclusions
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
Introduction: data storage/Er3+ excitation
Intro I: Optical data storage
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
Need for all-optical data storage writing, reading and erasing by photons
...
write
read
electronics
CDProcess of writing Thermal in nature (melt, cool down)
All optical process All optical process FAST FAST
Approaches:
- Holographic optical storage (IBM, Lucent)
- Hole burning
Optical memory effect observed in III-V semicond., but never in SiOptical memory effect observed in III-V semicond., but never in Si
Motivation for using Si
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
Why Si?Why Si?
King of electronicsKing of electronics
Environmentally friendlyEnvironmentally friendly
Total control of dopantsTotal control of dopants
potential for photonics?potential for photonics?(Integration of electronics and photonics, on-chip)(Integration of electronics and photonics, on-chip)
Motivation for using erbium (Er)
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
Why Er?Why Er?
Are there other rare earth (RE) elements available?Are there other rare earth (RE) elements available?
Inner 4f-electron shell transitionsInner 4f-electron shell transitions
Emission at 1.54 Emission at 1.54 m (telecommunications)m (telecommunications)
Sharp transitions in wavelengthSharp transitions in wavelength
Almost independent of host materialAlmost independent of host material
Silicon doped with rare earths
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Ce3+ Pr3+ Nd3
+ Pm3+ Sm3+ Eu3+ Gd3+ Tb3+ Dy3+ Ho3+ Er3+ Tm3+ Yb3+
RE ground state
Si bandgap
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
Er3+ excitation in an insulator (SiO2)
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
Er3+ ion
Direct Er3+ excitation 10-21 cm-2
All erbium can be excited
OPTICALLY
Er PL @ 1.54 m
We need laser to pump Er.
We need resonant energies.
ELECTRICALLY
Electron impact excitation10-14 cm-2
LED with quantum efficiencies 10 % (similar to III-V semicond.)
STMicroelectronics“New York Times, Oct. 2002 ”
Patent by STM
Er 12 ms
Solution ? Use sensitizers like nc-Sinc-Si
BAD !
EDFA
Optical Er3+ excitation sensitized with nc-Si
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
Ernc-Sinc-Si
Current investigations are based on:
-Excitation spectroscopy (power and wavelength dependence) CW or pulsed
-Kinetics (rise time, decay time), temperature dependence…
Dr. Wojdak ;-)
How many optically active Er? , Excitation cross section?,
Excitation/ Energy transfer mechanism?, Possibility to obtain GAIN?
Er
Optical Er3+ excitation in crystalline Si
Indirect excitation 10-15 cm-2 increased 6 orders of magnitude !
Generation of carriers optically band-to-band excitation E > Egap (1170 meV) (also possible electrically)
Er3+ ion
Nd
:YA
G
VB
CBCB
Er-related allows recombination level (electron and hole) Er3+ excitation
Role of shallow traps excitation / de-excitation? Mid infrared radiation
Source FREE ELECTRON LASER
Er-related
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
Er 1 ms
Er3+ de-excitation in crystalline Si
Back-transfer Provided by E (thermally or by FEL )
Ionization of traps may induce excitation or Auger de-excitation
Er3+ ion
VB
CB
Er-related
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
+E
Thermal effects quench completely RT emission Thermal effects quench completely RT emission at 1.54 at 1.54 mm
Er3+ ion Er3+ ion
Energy migrationEnergy migrationEr3+ ion Er3+ ion
Up-conversionUp-conversion
> Egap
Free Electron Laser (FEL) facility
High brilliance and precise energy tuning: (70-170) meV
The magnetic field generates periodically curved electron trajectory
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
The induced oscillating dipole moment leads to emission of radiation
Photoluminescence experimental set-upT = 4.2 K
sample
Ge
/ PM
T
emission @ 1.54 emission @ 1.54 mm
SpectrometerSpectrometer
Follow changes in:- Spectrum- Amplitude- Kinetics
Tunable delay time (t) and variable power
Nd:YAG (532 nm)Nd:YAG (532 nm)
FEL (10 FEL (10 m )m ) t
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
Experimental set-up (real one)
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
1500 1550 1600 1650
Er ions implanted: energy: 300 keV dose: 3*1012 cm-2
Er-concentration: 5*1017cm-3
Oxygen ions co-implanted: energy: 40 keV dose: 3*1013 cm-2
annealing: 900 oC (N2 atmosphere) time: 30 minutes.
Inte
nsit
y
Wavelength (nm)
1.5 m
0 10 20 30
Time (ms)
Inte
nsit
y a
t 1.5
m
1 ms
Photoluminescence of Si:Er
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
0 5 10 15
Nd:YAG
Time (ms)
PL
at 1
.54 m
(ar
b. u
nits
)
FEL
Afterglow and Er PL enhancement
Er PLEr PL
Nd:YAG
FEL
afterglow 100-150 ms
4.2 K
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
No effect when FEL is fired before Nd:YAG
0 50 100 150 200
enhancement
~ 150 ms
FEL
FELFEL
E
r P
L at
1.5
4 m
(ar
b. u
nits
)
Time (ms)
Dynamics of the enhancement effect
afterglow enhancement
M. Forcales et al., Phys. Rev. B 65, 195208 (2002)
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
Model
VB
CB
Er3+
matrixN
d:Y
AG
, A
r+
FEL
Er-related level
Er PL
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
Temperature dependence
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
0 5 10 15 20
t
1 2
Time (ms)
PL
at 1
.54 m
(ar
b. u
nits
)
0 5 10 15 20
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Time (ms)
PL
at
1.5
4
m (
no
rma
lize
d) 20 K
30 K
Single carrier excitation
0.00 0.01 0.02 0.03 0.04 0.05
PL
at 1
.54 m
(no
rmal
ized
)
Power FEL (normalized)
0.0 0.2 0.4 0.6 0.8 1.0
Power FEL (normalized)
P
L a
t 1
.54
m
(n
orm
aliz
ed
)
Enhancement effect does not follow (IFEL)2, quadratic dependence
Er3+ ion
VB
CBCB
Er-related
IFEL
Incorrect Model
M. Forcales et al., Phys. Rev. B 67, 0853xx (2003)
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
0.0 0.2 0.4 0.6 0.8 1.0
0.0
0.5
1.0
1.5
2.0
2.5
MIR photon flux
En
han
cem
en
t am
plitu
de
FEL = 14 m
fits the trap-ionization dependence:
p = (-II+sqrt(I2I2+4I cINtr))/2c
Dependence on flux
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
Ionization of traps
Enhancement has a dependence related to one carrier excitation
Concept of a Si-based optical storage element
Storage array Storage element
Writing beam λ1
(band-to-band)
Recovered signal at 1.54 m
Reading beam λ2
(below band gap)
M. Forcales et al., Solid State Electronics, vol. 47, 165 (2003)
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
Futures perspectives
--Need to improve thermal stability!Need to improve thermal stability!How? Using deeper acceptor traps (Zn, Mg).How? Using deeper acceptor traps (Zn, Mg).
-No need to use free electron laser!-No need to use free electron laser!How? Table-top OPO, COHow? Table-top OPO, CO22 or cascade lasers… or cascade lasers…
-Creation of electrons and holes separated in Creation of electrons and holes separated in time!time!How? Prepare the system by proper injection How? Prepare the system by proper injection of carriers.of carriers.
VB
CBCB
Er-related
Atr
Si-based optical elements could find applications in:Si-based optical elements could find applications in:- Telecommunication networks at 1.54 - Telecommunication networks at 1.54 mm- Optical storage devices for use in all-photonic - Optical storage devices for use in all-photonic technologytechnology- Quantum computing ?…- Quantum computing ?…
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________
Conclusions
Observation of afterglow and optical memory Observation of afterglow and optical memory effect in Si:Er system at temperatures T < 50 Keffect in Si:Er system at temperatures T < 50 K
The effect is a fundamental property of silicon The effect is a fundamental property of silicon (revealed by the optical dopant Er)(revealed by the optical dopant Er)
Proper engineering, will allow long time storage Proper engineering, will allow long time storage and thermal stabilityand thermal stability
_____________________Van der Waals-Zeeman Institute, University of Amsterdam________________
___________________________________________Group meeting, Feb. 2003_____________________________________________