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E mission C hanneling with S hort- L ived I sotopes: lattice location of impurities in semiconductors and oxides. - PowerPoint PPT Presentation
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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
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
emission channeling technique- decay, CE
electron yield
angle
emission channeling technique
electron yield
angle
electron yield
L.M.C. Pereira, INTC meeting, CERN, 25.10.2013
emission channeling techniqueNewsletter of the Faculty of Science - KU Leuven (Sept.-Nov. 2013)
L.M.C. Pereira, INTC meeting, CERN, 25.10.2013
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)
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
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)
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
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)
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]
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.
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