SPECIAL TOPICS IN ION BEAM ANALYSIS PART 2 SINGLE ION TECHNIQUES: - - PowerPoint PPT Presentation

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SPECIAL TOPICS IN ION BEAM ANALYSIS PART 2 SINGLE ION TECHNIQUES: - - PowerPoint PPT Presentation

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SPECIAL TOPICS IN ION BEAM ANALYSIS PART 2 SINGLE ION TECHNIQUES: STIM & IBIC Milko Jaki Laboratory for Ion Beam Interactions, Experimental physics division Ruer Bokovi Institute Zagreb, Croatia Ion Beam Analysis &

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SLIDE 1

SPECIAL TOPICS IN ION BEAM ANALYSIS – PART 2 SINGLE ION TECHNIQUES: STIM & IBIC

Milko Jakšić Laboratory for Ion Beam Interactions, Experimental physics division Ruđer Bošković Institute Zagreb, Croatia

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SLIDE 2

Ion Beam Analysis & NUCLEAR MICROPROBE

Charge pulse Recoil nuclei Transmitted particles Forward scattered particles Light X-rays

 rays

Backscattered particles TARGET Ion beam Nuclear reaction products Secondary electrons

ANALYSIS (elements, isotopes) with MeV ION BEAMS - (nA, pA)

  • elements - x-rays (PIXE)
  • backscattering (RBS)
  • recoil (ERDA)
  • isotopes - nuclear reactions

 - rays (PIGE) particles (NRA) CHARACTERISATION (density, charge transport, crystal structure, morphology,…) with MeV SINGLE IONS - (fA)

  • density - transmitted ions (STIM)
  • charge transport - charge pulse (IBIC)
  • crystal structure - channelling
  • morphology - secondary electrons (SEI)
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SLIDE 3

Single ion implantation

Why single ions?

  • Implantation of one particular atom

at exactly known position in exactly known time seems to be extremely attractive!

  • And it is easy (to perform

experimentaly) !

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SLIDE 4

Single ion implantation

Why single ions?

  • Implantation of one particular atom

at exactly known position in exactly known time seems to be extremely attractive!

  • And it is easy (to perform

experimentaly) !

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SLIDE 5

Single ions – ionisation & defects

Every ion:

  • Implants itself into

the substrate

  • Ionises many atoms
  • n its way - creates

large number of charge pairs Heavy ions:

  • Create many

vacancies

  • Some secondary

electrons

  • Some desorbed

molecules

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SLIDE 6

Accelerator & nuclear microprobe

Ideal radiation source

X Y proton beam scan generator X Y quadrupole doublet focusing lens sample

  • bject slits

IBIC signal IBIC - charge

collection efficiency

images

protons alphas

7Li 12C 16O

 IONS

  • p, , Li, C, O,..

 RANGE

  • 2 to 200 m

 ION RATE

  • currents 0 - 106 p/s

 ION POSITION

  • focusing and scanning
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SLIDE 7

Accelerator & nuclear microprobe

Available ion beams

Silicon I 127‐ Si 28 C 12 He 4 H 1 Range(µm) E=1 MeV 0.37 1.13 1.6 3.5 16.3 Range (µm) E=10 MeV 3.7 4.8 9.5 69.7 709

AT RBI ‐ terminal voltages – 0.1 to 6 MV Ion sources – sputtering, RF alphatross, duoplasmatron Good selection of ion ranges / dE/dx !!

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SLIDE 8

Single ion characterisation:

STIM – Scanning Transmission Ion Microscopy:

imaging of areal densities (dE/dx)

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SLIDE 9

STIM – Scanning ion transmission microscopy

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SLIDE 10

STIM – Scanning ion transmission microscopy

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SLIDE 11

STIM – Scanning ion transmission microscopy

10 µm

STIM image of copper grid using 8 MeV O3+ ions

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SLIDE 12

STIM – Scanning ion transmission microscopy

Density map for flies wing: 6 MeV O ions (left) and 2 MeV protons (right)

Track shape characterisation

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SLIDE 13

STIM – Scanning ion transmission microscopy

11 MeV 12C3+ ions high energy loss d ~ 1.68 m low energy loss d ~ 1.45 m Combination of STIM with 3D analysis using C ion induced coincidence spectroscopy O distribution and concentration in z direction ‐ small sample dimensions ~ 15 mm

Bi2Sr2CaCu2O8+ whiskers

17.7 m x y z

  • n axis STIM

28×28 m2

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SLIDE 14

Channeling STIM

STIM (transmission) channeling

  • currents ≈ 1 fA radiation

damage can be neglected

  • but, only transmission samples

 channeled ions  nonchanneled ions

E0

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SLIDE 15

Ion beam induced charge - IBIC

a) Ions lose their energy dE/dx b) Creation of charge pairs e/h

Depth (m) 5 10 15 20 25 Energy loss (keV/m) 100 200 300 400 500 600 700 800 2 MeV -particles 2 MeV protons

                  

2 2 2 2 2 2 2 4

1 ln 2 ln 4 c v c v I v m NZ v m z e dx dE 

Bethe formula: ions electrons

+

  • +

+ + + + + +

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SLIDE 16

Ion beam induced charge - IBIC

  • 1. for E  0 charge drift

+

  • +

+ + + + + +

                         

 

h h e e

d x h d x e

e L d e L d Q Q 1 1                          

 

h h e e

d x h d x e

e L d e L d Q Q 1 1

di = ()iE di = ()iE

  • Charge carriers produced along

the ion path drift in electric field

  • Charge pulse height depends
  • n the local value of electric field,

mobility and lifetime of charge carriers.

  • Collection length
  • for constant E,

Induced charge signal corresponds to the value of 

  • 2. for E = 0 charge diffuse

dx x x r x dx dE dx x dx dE Y

e

x L

d i d d

        

  

 

) (

dx x x r x dx dE dx x dx dE Y

e

x L

d i d d

        

  

 

) (

diffusion region drift region

+ ‐

a) Ions lose their energy dE/dx b) Creation of charge pairs e/h c) Charge transport: 1. Drift - in electric field 2. Diffusion d) Induced charge e) IBIC signal

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SLIDE 17

Ion beam induced charge - IBIC

a) Ions lose their energy dE/dx b) Creation of charge pairs e/h c) Charge transport: 1. Drift - in electric field 2. Diffusion d) Induced charge e) IBIC signal

V Q V

Vout

d

T= 0

  • 2

2 4 6 8 10 12 14 0.000 0.025 0.050 0.075 0.0 0.2 0.4 0.6 0.8 1.0

I Time Q

Induced current Induced charge

v

d v q ) t ( I  

T

dt ) t ( I ) t ( Q

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SLIDE 18

Ion beam induced charge - IBIC

a) Ions lose their energy dE/dx b) Creation of charge pairs e/h c) Charge transport: 1. Drift - in electric field 2. Diffusion d) Induced charge e) IBIC signal

V Q V

Vout

d

T=10

Induced current Induced charge

v

d v q ) t ( I  

T

dt ) t ( I ) t ( Q

  • 2

2 4 6 8 10 12 14 0.000 0.025 0.050 0.075 0.0 0.2 0.4 0.6 0.8 1.0

I Time Q

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SLIDE 19

Ion beam induced charge - IBIC

  • 2

2 4 6 8 10 12 14 16 0.000 0.025 0.050 0.075 0.0 0.2 0.4 0.6 0.8 1.0

I Time Q

T

dt ) t ( I ) t ( Q

  • 2

2 4 6 8 10 12 14 0.000 0.025 0.050 0.075 0.0 0.2 0.4 0.6 0.8 1.0

I Time Q

             t d v q t I exp ) (

In reality  (charge carrier lifetime) can be short due to defects !

Velocity; v dTR Mobility; d2/(TR *VBias)

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SLIDE 20

Ion Beam Induced Charge

Pulse processing (visit ORTEC tutorial)

Charge sensitive preamplification ‐ For high resolution PHA (pulse height analysis) ‐ Due to integration, time structure of the signal is forgotten ‐ Shaping time constant Current preamplifier ‐ For studying of pulse time structure – TRIBIC)

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SLIDE 21

t(s)

  • 1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 VO(mV)

  • 2

2 4 6 8 10 12 14 16 18 20

  • 100 V
  • 200 V
  • 40 V
  • 80 V
  • 1000 V

Electron mobility: e= 781 cm2/Vs V t d

r 2

 

CdZnTe

Output from the charge senistive preamlifier at digital osciloscope ions

  • +

Ion Beam Induced Charge

Pulse processing (time resolved IBIC)

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SLIDE 22

Ion beam induced charge - IBIC

250 nm

IBIC spatial resolution  down to 0.25 μm

Frontal IBIC on polyCVD diamond

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SLIDE 23

EFG silicon Schotky diode Frontal IBIC images can identify distribution of electrically active defects !

Ion beam induced charge

Frontal IBIC

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SLIDE 24

Ion beam induced charge

Frontal IBIC

By proper selection of ion type and energy, CCE (charge collection efficiency) at different sample depths can be imaged.

4.5 MeV Li range 6μm 3 MeV protons range 90 μm

Si Schotky diode surface bulk

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SLIDE 25

Ion beam induced charge - IBIC

Lateral IBIC on Si power diode

E = 0

contact and/or heavily doped region pn junction

E < 0

ion beam zd z (z<zd) = 1 (z>zd) = exp(‐(z‐zd)/Lp,n)

hole or electron diffusion length

50 100 150 200 250 0,08 0,1 0,1 0,2 0,4 0,6 0,8 1

Lp = ( 27.3 ± 0.8 ) m

 = (0.57 ± 0.03)s

117.5 V 90.6 V 60.4 V 28 V Collection efficiency Depth (m)

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SLIDE 26

CdZnTe

U=+50V ST=2.0s U=+100V ST=2.0s U=+150V ST=2.0s U=+250V ST=2.0s U=+50V ST=8.0s U=+100V ST=8.0s U=+150V ST=8.0s U=+250V ST=8.0s

In-Au ST=8s

depth (m)

250 500 750 1000 1250 1500 1750 2000

efficiency (%)

0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0

+50V +100V +150V +200V +250V

electrons holes electrons holes

ion beam

CCE 100%

fully depleted device (ideal case)

Ion beam induced charge - IBIC

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SLIDE 27

Ion beam induced damage

dE/dx – nuclear stopping

dE/dx of Xe ions in silicon

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SLIDE 28

50 Li7 m‐2 = 5 109 cm‐2 6 Li7m‐2 = 6 108 cm‐2 (4 events per pixel)

  • For 100% ion impact detection efficiency, IBIC

can be used to monitor irradiation fluence

  • Irradiation of arbitrary shapes
  • On‐line monitoring of CCE degradation

Ion microprobe irradiation & IBIC probing

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SLIDE 29

Ion microprobe irradiation & IBIC probing

  • By excessive irradiation of small detector regions

(e.g. 50 x 50 μm2) induced defects (charge carrier traps) degrade charge collection efficiency (CCE)

  • Irradiation fluence and CCE are continuously

monitored on-line

  • Damaging/probing concept can be used for

radiation hardness tests (e.g Si vs. diamond)

  • V. Grilj et al (RBI, JAEA)
  • Nucl. Instr. Meth. B306 (2013) 191
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SLIDE 30

Ion beam induced charge - IBIC

1E11 1E12 1E13 1E14 0.5 0.6 0.7 0.8 0.9 1.0

scCVD (150V) membrane (80V) membrane (15V)

CCE

d [MeV/g]

scCVD diamond membrane detector

CVD diamond membrane provides a trigger for each single ion transmitted to the air Extreme radiation hardness – equivalent of 1016 cm-2 of 1 MeV neutrons !!

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SLIDE 31

Ion beam induced charge - IBIC

CCE = 1 – D* kσ kσ je svojstvo materijala D* efektivna doza Zaključak da je otpornost na zračenje silicija i dijamanta vrlo slična !

Diamond: V. Grilj et al, Nucl.

  • Instr. Meth. B372 (2016) 161

Silicij: Ž. Pastuović et al, Appl.

  • Phys. Lett. 98 (2011) 092101
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SLIDE 32

Samples:

  • Si PIN diode Hammamatsu S1223
  • 4H-SiC Schottky diode

Probing the defect creation process (Si and SiC)

Pulsed beam

Irradiation and IBIC probing:

  • 3.25 MeV C ions (both irradiation

and IBIC probing

  • Ion range 3.5 μm in Si ( as for 1

MeV He ions )

  • ton = 1 ms; toff = 0.1 to 50 ms
  • fluence:

346 μm-2 (Si) 33 μm-2 (SiC)

  • 400 pulses

System is typicaly used for MeV SIMS & single ion implantation, irradiation and probing is controlled by SPECTOR

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SLIDE 33

Samples:

  • Si PIN diode Hammamatsu S1223
  • 4H-SiC Schottky diode

Probing the defect creation process (Si and SiC)

Pulsed beam

Irradiation and IBIC probing:

  • 3.25 MeV C ions (both irradiation

and IBIC probing

  • Ion range 3.5 μm in Si ( as for 1

MeV He ions )

  • ton = 1 ms; toff = 0.1 to 50 ms
  • fluence:

346 μm-2 (Si) 33 μm-2 (SiC)

  • 400 pulses

System is typicaly used for MeV SIMS & single ion implantation, irradiation and probing is controlled by SPECTOR

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SLIDE 34

Probing the defect creation process (Si and SiC)

Pulsed beam

Irradiation and IBIC probing:

  • 3.25 MeV C ions (both irradiation

and IBIC probing

  • Ion range 3.5 μm in Si ( as for 1

MeV He ions )

  • ton = 1 ms; toff = 0.1 to 50 ms
  • fluence:

346 μm-2 (Si) 33 μm-2 (SiC)

  • 400 pulses

Si pin 4H SiC Average distance between ions within a single pulse was > 1 μm .... too large for ‘dynamic annealing’ of defects No statisticaly significant changes have been observed for different ton/toff cycles (millisecond range)

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SLIDE 35

In air IBIC experiment

  • Large detector structures (e.g. high energy physics

detectors) can not be tested in small vacuum chamber

  • Alternative – in air microbeam !
  • But - beam spot degradation

Degradation of beam spot (in micrometers) for SiN and diamond exit foil

  • SOLUTION:
  • SiN exit foil
  • up to 2 mm working distance
  • Proton energy > 6 MeV !!

Energy / air path 100 nm Si3N4 6 µm diamond 3 MeV / 0.5 mm 1.02 9.0 3 MeV / 2.0 mm 4.39 30.6 6 MeV / 0.5 mm 0.50 4.3 6 MeV / 2.0 mm 2.06 14.8 9 MeV / 0.5mm 0.34 2.9 9 MeV / 2.0 mm 1.40 9.9

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SLIDE 36

Si pin diode