Twocolor midinfrared

1
_____________________Van der Waals-Zeeman
Institute, University of Amsterdam________________
_____
Two-color mid-infrared spectroscopy of
isoelectronic centers in silicon
N.Q. Vinh Van der Waals - Zeeman
Institute, University of Amsterdam, The
Netherlands
___________________________________MRS 2003
SPRING MEETING___________________________________
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_____________________Van der Waals-Zeeman
Institute, University of Amsterdam________________
_____
Introduction
PL intensity (arb. units)
SiAg
SiCu
Photon energy (meV)
Photon energy (meV)
?1 114 ?s
?1 265 ?s
PL intensity (arb. units)
10 K
10 K
SiAg
SiCu
Time (?s)
Time (?s)
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_____________________Van der Waals-Zeeman
Institute, University of Amsterdam________________
_____
Emission due to exciton bound to an
isoelectronic center
CB
Bound exciton
340 meV
VB
Excitation pathway of a bound exciton system
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_____________________Van der Waals-Zeeman
Institute, University of Amsterdam________________
_____
Spectroscopy in the mid-infrared
Illumination with high-flux mid-infrared radiation
CB

• Ionization of (shallow) traps
• selective manipulation of shallow traps

Eph

• Time-resolved measurements
• study of dynamics

VB
Excitation pathway of a bound exciton system

• All at low T

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_____________________Van der Waals-Zeeman
Institute, University of Amsterdam________________
_____
Free Electron Laser FELIX facility
Range I 7-18 ?m (70-170 meV) Range II 20-40 ?m
(35-65 meV)
___________________________________MRS 2003
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_____________________Van der Waals-Zeeman
Institute, University of Amsterdam________________
_____
Experimental Set-up
NdYAG (? 532 nm)
Cryostat
FEL
Sample

• tunable delay time ?t -100ms to 100ms
• variable power
• ?MIR 7.0 - 40.0 ?m (35 - 170 meV)

Spectrometer
PMT
time-resolvedtwo-color spectroscopy
___________________________________MRS 2003
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_____________________Van der Waals-Zeeman
Institute, University of Amsterdam________________
_____
SiAg - PL Quenching with FEL
_at_ 88 meV and 3 dB
PL intensity (arb. units)
Range I
Time (?s)
Quenching effect can be induced only after
primary excitation
___________________________________MRS 2003
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_____________________Van der Waals-Zeeman
Institute, University of Amsterdam________________
_____
SiAg - PL Quenching with FEL
_at_ 50 meV and 5 dB
PL intensity (arb. units)
Range II
Time (?s)
The quenching effect is transient PL recovers
when FEL is turned off
___________________________________MRS 2003
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_____________________Van der Waals-Zeeman
Institute, University of Amsterdam________________
_____
SiCu - PL Quenching with FEL
_at_ 88 meV and 25 dB
PL intensity (arb. units)
Range I
Time (?s)
Quenching effect can be induced only after
primary excitation
___________________________________MRS 2003
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_____________________Van der Waals-Zeeman
Institute, University of Amsterdam________________
_____
SiCu - PL Quenching with FEL
_at_ 50 meV and 10 dB
PL intensity (arb. units)
Range II
Time (?s)
No signal recovery after FEL pulse terminates
___________________________________MRS 2003
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_____________________Van der Waals-Zeeman
Institute, University of Amsterdam________________
_____
The quenching effect
PL quenching depends on ?FEL
FEL flux depends on ? FEL
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_____________________Van der Waals-Zeeman
Institute, University of Amsterdam________________
_____
Quenching by FEL SiAg
Quench ratio (arb. units)
Eion ? 33 meV
Photon energy (meV)
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_____________________Van der Waals-Zeeman
Institute, University of Amsterdam________________
_____
Quenching by FEL SiCu
Eion ? 32 meV Eion ? 36 meV
Quench ratio (arb. units)
Photon energy (meV)
___________________________________MRS 2003
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_____________________Van der Waals-Zeeman
Institute, University of Amsterdam________________
_____
Model
SiAg EPL 780 meV Eion 33 meV
Eloc 357 meV SiCu EPL 944 meV
Eion 32 meV Eloc 194 meV Eion
36 meV Eloc 190 meV
Eg 1170 meV
Ag (Cu)
780 meV
Ionization of the secondary particle of a bound
exciton system
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_____________________Van der Waals-Zeeman
Institute, University of Amsterdam________________
_____
Conclusions
Confirmation the microscopic model of an exciton
bound to an iso-electronic center
Binding energy of an electron in an
effective-mass-theory shallow trap is measured
spectroscopically
From the spectrum analysis, the primary particle
bound at TM-related center has a strong potential.
___________________________________MRS 2003
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_____________________Van der Waals-Zeeman
Institute, University of Amsterdam________________
_____
Acknowledgements
Group members WZI M. Forcales, M.A.J. Klik, M.
Wojdak, I. Izeddin, T. Gregorkiewicz FOM
Institute Rijnhuizen I. Bradley, J.P. Wells,
J. Phillips Collaboration Gordon Davies, Kings
College, London UK
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