E mission C hanneling with S hort- L ived I sotopes: lattice location of impurities in...
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Emission Channeling with Short-Lived Isotopes: lattice location of impurities in semiconductors and oxides
L.M.C. Pereira1 , L. Amorim1, J.P. Araújo4, V. Augustyns1, K. Bharuth-Ram6, E. Bosne5, J.G. Correia2, A. Costa2, P. Miranda7, D.J. Silva4, M.R. da Silva3, K. Temst1, A. Vantomme1, and U. Wahl2
spokesperson: L.M.C. Pereiracontact person: J.G. Correia
1 Instituut voor Kern- en Stralingsfysica (IKS), KU Leuven, 3001 Leuven, Belgium2 Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, 2686-953 Sacavém, Portugal3 Centro de Física Nuclear da Universidade de Lisboa (CFNUL), 1649-003 Lisboa, Portugal4 Departamento de Física, Universidade do Porto, 4169-007 Porto, Portugal5 Departamento de Física, Universidade de Aveiro, 3810-193 Aveiro, Portugal6 University of KwaZulu Natal, Durban 4041, South Africa7 Departamento de Física, Universidad de Chile, Las Palmeras 3425, Santiago, Chile
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motivation and outlineLattice location experiments on semiconductors and oxides of fundamental and technological relevance• Transition metals in dilute magnetic semiconductors
isotopes: 56Mn (t1/2=2.6 h), 59Fe (45 d), 61Co (1.6 h) and 65Ni (2.5 h)
• p-type dopants in nitride semiconductors isotopes: 27Mg (9.5 min) and 11Be (13.8 s)
• Positron emitter 11C (20.4 min) for β+ emission channeling (feasibility)
Part of a wide research program involving complementary large-scale facility techniques
• Synchrotron radiation• Neutron scattering
L.M.C. Pereira, INTC meeting, CERN, 25.10.2013
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emission channeling technique- decay, CE
electron yield
angle
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emission channeling technique
electron yield
angle
electron yield
L.M.C. Pereira, INTC meeting, CERN, 25.10.2013
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emission channeling techniqueNewsletter of the Faculty of Science - KU Leuven (Sept.-Nov. 2013)
L.M.C. Pereira, INTC meeting, CERN, 25.10.2013
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dilute magnetic semiconductors (DMS)“Classic” DMS
• Mn-doped narrow-gap III-Vs (GaAs, InAs, …) Key question: interstitial Mn site-change and migration Experiments: low-T 56Mn in Ga1-xMnxAs (Nottingham)
L.M.C. Pereira, INTC meeting, CERN, 25.10.2013
previous work on the low concentration regime:
L.M.C Pereira et al., Appl. Phys. Lett. 98, 201905 (2011)L.M.C Pereira et al., Phys. Rev. B 86, 125206 (2012)
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dilute magnetic semiconductors (DMS)“Classic” DMS
• Mn-doped narrow-gap III-Vs (GaAs, InAs, …) Key question: interstitial Mn site change and migration Experiments: low-T 56Mn in Ga1-xMnxAs (Nottingham)
• TM-doped wide-gap oxides and nitrides (ZnO, GaN,…) Key question: anion substitutional TMs: why/how?
Experiments: 56Mn/ 59Fe in Mn/Fe-doped GaN and Al1-xGaxN (Linz)
L.M.C. Pereira, INTC meeting, CERN, 25.10.2013
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dilute magnetic semiconductors (DMS)“Classic” DMS
• Mn-doped narrow-gap III-Vs (GaAs, InAs, …) Key question: interstitial Mn site change and migration Experiments: low-T 56Mn in Ga1-xMnxAs (Nottingham)
• TM-doped wide-gap oxides and nitrides (ZnO, GaN,…) Key question: anion substitutional TMs: why/how?
Experiments: 56Mn/ 59Fe in Mn/Fe-doped GaN and Al1-xGaxN (Linz)
L.M.C. Pereira, INTC meeting, CERN, 25.10.2013
previous work on the low concentration regime:
L.M.C Pereira et al., Phys. Rev. B 84, 125204 (2011)
L.M.C Pereira et al., Phys. Rev. B 86, 195202 (2012)
L.M.C Pereira et al., Appl. Phys. Lett. 103, 091905 (2013)
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dilute magnetic semiconductors (DMS)“Novel” DMS• Transition metal doped ternary oxides
Key question: single-ion ferromagnetism Experiments: 56Mn/59Fe/61Co/65Ni
in SrTiO3, LiNbO3…
Theory: G. F. Dionne (MIT)
-2
-1
0
1
2
-2 -1 0 1 2
(a)
{100}
{110}
experiment-2 -1 0 1 2
1.29 - 1.36 1.23 - 1.29 1.16 - 1.23 1.10 - 1.16 1.03 - 1.10 0.97 - 1.03 0.91 - 0.97 0.84 - 0.91
best fit STi + STiSO + I8
(e) <100>
-2
-1
0
1
2
{211}
{111}(b){110}
1.52 - 1.61 1.43 - 1.52 1.34 - 1.43 1.25 - 1.34 1.16 - 1.25 1.07 - 1.16 0.98 - 1.07 0.89 - 0.98
(f) <110>
-2
-1
0
1
2(c)
{210}
{110}
1.29 - 1.36 1.23 - 1.29 1.16 - 1.23 1.10 - 1.16 1.03 - 1.10 0.97 - 1.03 0.91 - 0.97 0.84 - 0.91
(g) <211>
[deg]-2 -1 0 1 2
-2
-1
0
1
2
{211}
(d)
{110}
-2 -1 0 1 2
(h) <111> 1.14 - 1.18 1.11 - 1.14 1.07 - 1.11 1.03 - 1.07 1.00 - 1.03 0.96 - 1.00 0.93 - 0.96 0.89 - 0.93
L.M.C. Pereira, INTC meeting, CERN, 25.10.2013
undoped SrTiO3Fe in ideal Ti sites
in Sr(Fe,Ti)O3
Fe in displaced Ti sitesin Sr(Fe,Ti)O3
X-ray absorption fine structureNuclear resonant scatteringX-ray magnetic circular dichroismSynchrotron radiaction X-ray diffractionPolarized neutron reflectivty
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p-type dopants in nitrides• 27Mg and 11Be in GaN, AlN, InN Key questions: precise lattice location of acceptors
andthe relation to hole localization and self-compensation
Experiments: 27Mg: higher angular resolutionlow-temperature
11Be: new isotope
L.M.C. Pereira, INTC meeting, CERN, 25.10.2013
our previous work (27Mg:GaN/AlN):
L.M. Amorim et al., submitted to Phys. Rev. Lett.L.M. Amorim et al., submitted to Appl. Phys. Lett.
J.L. Lyons et al., Phys. Rev. Lett. 108, 156403 (2012)
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p-type dopants in nitrides• 27Mg and 11Be in GaN, AlN, InN Key questions: precise lattice location of acceptors
andthe relation to hole localization and self-compensation
Experiments: 27Mg: higher angular resolutionlow-temperature
11Be: new isotope
L.M.C. Pereira, INTC meeting, CERN, 25.10.2013
feasibility11Be:GaN
-1.5 -1.0 -0.5 0.0 0.5-1.5
-1.0
-0.5
0.0
0.5
-1.0 -0.5 0.0 0.5 1.0
(1-1
01)
(11-20)
-1.0 -0.5 0.0 0.5 1.0
(1-1
02)
(11-20)
-1.0 -0.5 0.0 0.5 1.0[°]
11Be in GaN
(2-1
-12)
(41 -5 0 )
1.12 - 1.15 1.10 - 1.12 1.07 - 1.10 1.04 - 1.07 1.02 - 1.04 0.99 - 1.02 0.97 - 0.99 0.94 - 0.97
(01-10)
[-2113][-1101][-1102][0001]
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11C β+ emission channeling• Case-study for positron emission channeling• Relevant for:
o Dopant/contaminant in semiconductors/metalso Graphene growth (e.g. C-implanted Ni)o Implantation damage and annealing in SiC and diamondo …
-3 -2 -1 0 1 2 3-3
-2
-1
0
1
2
3
1.03 -- 1.12 0.95 -- 1.03 0.87 -- 0.95 0.78 -- 0.87 0.70 -- 0.78 0.61 -- 0.70 0.53 -- 0.61 0.44 -- 0.53
-3 -2 -1 0 1 2 3
(211
)
1.02 -- 1.09 0.95 -- 1.02 0.88 -- 0.95 0.82 -- 0.88 0.75 -- 0.82 0.68 -- 0.75 0.61 -- 0.68 0.54 -- 0.61
-3 -2 -1 0 1 2 3(211)
(111)
1.03 -- 1.12 0.95 -- 1.03 0.87 -- 0.95 0.78 -- 0.87 0.70 -- 0.78 0.61 -- 0.70 0.53 -- 0.61 0.44 -- 0.53
-3 -2 -1 0 1 2 3
(311)
(111
)
(110)
(100
)(110)(110
)(100)
(100)
1.03 -- 1.11 0.96 -- 1.03 0.88 -- 0.96 0.80 -- 0.88 0.72 -- 0.80 0.65 -- 0.72 0.57 -- 0.65 0.49 -- 0.57
(110)
<211><110><111><100>
L.M.C. Pereira, INTC meeting, CERN, 25.10.2013
Expected positron blocking patterns from
substitutional 11C in Si at room temperature for
11C16O+ implantation with 50 keV.
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beam requestisotope number
of shifts target ion source minimum yield [atoms/s/mA]
56Mn (2.6 h) 4 UCx-W RILIS Mn 5×107
61Mn (4.6 s)→ 61Fe (6 min)→ 61Co (1.6 h)
1 UCx-W RILIS Mn 2×106
59Mn (0.71 s)→ 59Fe (45 d) 1 UCx-W RILIS Mn 108
65Ni (2.5 h) 3 UCx-W RILIS Ni 5×107
27Mg (9.5 min) 12 Ti-W RILIS Mg 1×107
11Be (13.8 s) 6 UCx-W or Ta-W RILIS Be 6×106
11C (20 min) as 11C16O+ molecule 3 Molten salt,
NaF-LiF eutectic VD5 plasma 5×107
(achieved 7×108)
L.M.C. Pereira, INTC meeting, CERN, 25.10.2013
Total requested shifts: 30