Donor-Acceptor Complexes in ZnO
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Donor-Acceptor Complexes in ZnO M. Türker , M. Deicher, H. Wolf, and Th. Wichert Universität des Saarlandes Technische Physik, 66123 Saarbrücken The ISOLDE Collaboration CERN, Geneva, Switzerland
description
Donor-Acceptor Complexes in ZnO. M. Türker , M. Deicher , H. Wolf, and Th . Wichert. Universität des Saarlandes Technische Physik, 66123 Saarbrücken. The ISOLDE Collaboration CERN, Geneva , Switzerland. Zinc Oxide. E G = 3.37 eV at RT E exciton binding = 60 meV - PowerPoint PPT Presentation
Transcript of Donor-Acceptor Complexes in ZnO
Donor-Acceptor Complexes in ZnO
M. Türker, M. Deicher, H. Wolf, and Th. WichertUniversität des SaarlandesTechnische Physik, 66123 Saarbrücken
The ISOLDE CollaborationCERN, Geneva, Switzerland
Zn
O
Zinc Oxide
c-axis
EG = 3.37 eV at RT
Eexciton binding = 60 meV
Bulk crystal
Easy to dope n-type
Difficult to dope p-type2
Bulk crystalNO
Zn
O
InZn
NO
Donor-Acceptor CodopingYamamoto and Katayama-YoshidaPhysica B 302 (2001) 155
Donor-Acceptor Cluster-DopingWang and ZungerPhysical Review Letters 90 (2003) 256401
possibleIn-N2 complex
3
How to enhance p-type doping?
Chen, Lu, Ye, Lin, Zhao, Ye, Li, and ZhuApplied Physics Letters 87 (2005) 252106
How to enhance p-type doping?
Zn
O
InZn
NOElectrical properties of ZnO films
Sample Carriertype
Carrierconcentration
N doped p 3.25 1014 cm-3
In-Nx codoped p 3.51 1017 cm-3
Donor-Acceptor CodopingYamamoto and Katayama-YoshidaPhysica B 302 (2001) 155
Donor-Acceptor Cluster-DopingWang and ZungerPhysical Review Letters 90 (2003) 256401
possibleIn-N2 complex
increase byfactor 1000 3
Codoping with In and N by implantation
Park, Sakaguchi, Ohashi, Hishita, and HanedaApplied Surface Science 203-204 (2003) 359
Con
cent
ratio
n [io
ns/c
m3 ] 1020
1019
1018
1017
1016
0.0 0.4 0.8 1.2 0.0 0.4 0.8 1.2
asimplanted
TA=1073Kt=60min
N
N
SIMS depth profiling
depth [μm]
possibleIn-N2 complex
4
Zn
O
InZn
NO
In
InI n
I n
Perturbed Angular Correlation (PAC)
EFGlattice
111InZn
5
Electricalfield gradient Vij
- strength Vzz
- symmetry η =
- orientation
EFG ~ r – 3
- microscopic local
Zn
O NO
111InZn
Zn
O
EFGdefect
Vxx - Vyy
Vzz
Perturbed Angular Correlation (PAC)
6
T1/2 = 3 d
T1/2 = 85 ns
111In
111Cd
1
2Q
ECDonor-acceptor
interaction
Observation
Perturbed Angular Correlation (PAC)
T1/2 = 3 d
T1/2 = 85 ns
111In
111Cd
1
2Q
EC
EFG ≠ 0
ω1
ω3ω2
Q = w1=e Q Vzz
h103 p
Q: quadrupole coupling constant 6
Observation
Donor-acceptorinteraction
0 100 2000
10
20
FT
w [Mrad/s] 7
c-axis :
45°-geometry
detector
detector
Intrinsic EFGlattice of ZnO
0 100 2000
10
20
0 200 400 600
0.1
0.0
-0.1R(t) Fourier transforms
EFGlattice
Q = 31MHz = 0f = 86%
t [ns] w [Mrad/s]
111In implantation; TA = 1100K tA = 30min
0 200 400 600
0.1
0.0
-0.1
R(t)
t [ns]
0 100 2000
10
20
0 200 400 600
0.1
0.0
-0.1R(t) Fourier transforms
EFGlattice
Q = 31MHz = 0f = 86%
t [ns] w [Mrad/s]
Codoping of ZnO
Indium penetration in ZnO
E = 400 keV
depth 974 Å
(ato
ms/
cm3 )
/ (a
tom
s/cm
2 )
E = 220 keV
depth 3368 Å
N
(ato
ms/
cm3 )
/ (a
tom
s/cm
2 )
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Group V energy penetration depth N 220keV 3368Å P 400keV 3179Å As Sb 400keV 1228Å
In
111In implantation; TA = 1100K tA = 30min
0 200 400 600 8000
1
0 200 400 600 8000
1
Indium-Nitrogen codoping of ZnO
Q2
Q1
Q2
Q1
0 200 400 600
0.0
-0.1
0 200 400 600
0.0
-0.1
t [ns] w [Mrad/s]
FT(ω)R(
t)
FT(ω)R(
t)
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N (220keV) + 111In (400keV); TA = 1000K tA = 20min
0 200 400 600 8000
1
rb137_05
0 200 400 600 8000
1
rb137_06
c-axis orientedQ1=209(1)MHz=0f=2%
basal plane orientedQ2=234(1)MHz≤0f=5%
2 axial symmetricalEFGdefect:
0 200 400 600
0.0
-0.1
0 200 400 600
0.0
-0.1
t [ns] w [Mrad/s]
R(t)
R(t)
9
Q2Q1
FT(ω)
w [Mrad/s]
FT(ω)
Q2Q1
Indium-Nitrogen codoping of ZnON (220keV) + 111In (400keV); TA = 1000K tA = 20min
600 800 1000 12000246
40506070
f [%
]
TA [K]
f1
f2
f3
Isochronic annealing
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f2f1
f0
Indium-Nitrogen codoping of ZnO
0 200 400 6000
1
w [Mrad/s]
0 200 400 600
0.0
-0.1
0 200 400 6000
1
w [Mrad/s]
0 200 400 600
0.0
-0.1
t [ns] w [Mrad/s]
R(t)
Q2Q1
Q2Q1
R(t)
c-axis orientedQ1=153(1)MHz=0f=2%
basal plane orientedQ2=176(1)MHz≤0f=10%
FT(ω)
FT(ω)
2 axial symmetricalEFGdefect:
Indium-Phosphorus codoping of ZnOP (400keV) + 111In (400keV); TA = 800K tA = 60min
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Formation of Indium-Acceptor-Pairsin II-VI semiconductors
* Ostheimer, Jost, Filz, Lauer, Wolf, and WichertApplied Physics Letters 69 (1996) 2840
ZnO *ZnSe *ZnTe *CdTe
111In – N 209234 271 262 280
111In – P 153176 219 222 212
111In – As 196 199 186
111In – Sb 169 156 167 153
cubic
12* * Lany, Ostheimer, Wolf, and WichertHyperfine Interactions 136/137 (2001) 619
**CdTe
274
224
190
162
theoreticalwurtzite
Formation of Indium-Acceptor-Pairsin Zinc Oxide
Q [MHz] f [%] η Orientation
111In – N209 (1)
239 (1)
2
5
0
≤0.1
c-axis
basal plane
111In – P155 (1)
175 (1)
2
10
0
≤0.1
c-axis
basal plane
111In – Sb169 (1)
/
9
/
≤0.1
/
basal plane
13
In-N1
Possible configurations of In-NX Complexes=0 ≤0.1
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In-N2≠0 ≠0
In-N3≠0 =0 =0 In-N4
Summary
PAC
• In-N1: 2 EFG
• In-P1: 2 EFG
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Donor–acceptor codoping of ZnO by ion implantation
Aim: analysis of the microscopic environment on atomic level
Tool: Perturbed Angular Correlation to obtain structural information
Financial support by BMBF 05KK7TS116
Group I Acceptor
Li Na
K
77BrGroup VII
Donor
ISOLDE CERN
Implantations: Michael Uhrmacher and Daniel Jürgens (U Göttingen)
Work in progress77Br/ 77Se (60keV); TA = 1100K
0 20 40
0.0
-0.1
ct032_3
t [ns]
Q=403 MHz
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