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