Veljko Grilj Ru đ er Bošković Institute, Zagreb, Croatia Silicon Detector Workshop Split, Croatia, 8-10 October 2012

1.0 MV HVE Tandetron accelerator 6.0 MV EN Tandem Van de Graaff accelerator IAEA beam line TOF ERDA PIXE/RBS Dual-beam irradiation Ion microprobe Nuclear reactions In-air PIXE PIXE crystal spectrometer Det. test. IBIC 1 2

1. Beam deflector and/or scanner 2. Pre-chamber with beam degrader/diffuser 3. Final chamber with beam in air capability

 IONS - p, , Li, C, O,..  IONS - p, , Li, C, O,..  RANGE - 2 to 200  m  RANGE - 2 to 200  m  ION RATE - currents p/s  ION RATE - currents p/s  ION POSITION - focusing and scanning  ION POSITION - focusing and scanning

protons C Si Cu I E ions = 1 MeV/amu MIPs SiliconI 127Si 28C 12He 4H 1 Range(µm) E=1 MeV Range (µm) E=10 MeV Accel. voltages 0.1 to 6.0 MV Negative Ion sources: -Duoplasmatron -RF He -Sputtering

V Q V V out Ouput signal V out Deposited energy Principles of radiation detection techniques V out = F (deposited energy, free carrier transport) Nuclear spectroscopy Well known Free charge genetration and transport

V Q V V out Ouput signal V out Deposited energy Principles of IBIC V out = F (deposited energy, free carrier transport) Free charge genetration and transport Well knownMaterial characterization

Bethe formula: a) Energy deposition by ions Principles of IBIC b) Creation of e-h pairs

c) Free charge carrier transport → charge induced at electodes Principles of IBIC Gunn’s theorem: V Q V V out d T=0 v year 1964

c) Free charge carrier transport → charge induced at electodes Principles of IBIC Gunn’s theorem: V Q V V out d T=1

c) Free charge carrier transport → charge induced at electodes Principles of IBIC Gunn’s theorem: V Q V V out d T=2

c) Free charge carrier transport → charge induced at electodes Principles of IBIC Gunn’s theorem: V Q V V out d T=3

c) Free charge carrier transport → charge induced at electodes Principles of IBIC Gunn’s theorem: V Q V V out d T=4

c) Free charge carrier transport → charge induced at electodes Principles of IBIC Gunn’s theorem: V Q V V out d T=5

c) Free charge carrier transport → charge induced at electodes Principles of IBIC Gunn’s theorem: V Q V V out d T=6

c) Free charge carrier transport → charge induced at electodes Principles of IBIC Gunn’s theorem: V Q V V out d T=7

c) Free charge carrier transport → charge induced at electodes Principles of IBIC Gunn’s theorem: V Q V V out d T=8

c) Free charge carrier transport → charge induced at electodes Principles of IBIC Gunn’s theorem: V Q V V out d T=9

c) Free charge carrier transport → charge induced at electodes Principles of IBIC Gunn’s theorem: V Q V V out d T=10

c) Free charge carrier transport → charge induced at electodes Principles of IBIC Gunn’s theorem: V Q V V out d T=11

Impact of defects on charge carriers mobility: Principles of IBIC - physical opservable:

Principles of IBIC - direct implication from Gunn’s theorem: - consequences: electronsholes ion beam CCE 100% a) b) - V 0 he

Advantages of using focused ions: - spatial resolution - wide spread of ion ranges Principles of IBIC 20  m Electrons 10 keV Electrons 40 keV 2 MeV H+ in Si3 MeV H+ in Si 4 MeV H+ in Si 2  m 4  m 6  m 47  m 90  m 147  m

PIN diode Samples

CVD diamond CdInGaSe solar cell Si DSSD (16x16 strips) Ion beam Samples Laura Grassi, Wednesday, 16:00h

100  m Geometries

- 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 Frontal IBIC

4.5 MeV Li 7 ions (range in Si 8.5  m) O 16 ions (range in Si 4.5  m) Li image - O image / 2.8 IBIC between 4.5 and 8.5  m Frontal IBIC – depth profiling Si Schotky diode

Frontal IBIC – drift & diffusion drift diffusion E ≠ 0E = 0 minority carrier diffusion length 4H-SiC diode

drift diffusion E ≠ 0E = 0 Frontal IBIC – drift & diffusion 4H-SiC diode

drift diffusion E ≠ 0E = 0 Frontal IBIC – drift & diffusion 4H-SiC diode

drift diffusion E ≠ 0 - direct measurement of diffusion length L p = (9.0±0.3) μm Frontal IBIC – drift & diffusion 4H-SiC diode

Frontal IBIC – μτ mapping - from Gunn’s theorem with assumptions of full depletion, constant electric field and generation near one electrode: electrons holes Hecht equation CdZnTe - sample thickness > 2 mm - IBIC with 2 MeV p +, range < 30 μm M. Veale et al., IEEE TNS, 2008

Si power diode E = 0 pn junction E < 0 ion beam 0 zdzd z CCE (z<z d ) ≈ 1 CCE (z>z d ) = exp(-(z-z d )/L p,n ) hole or electron diffusion length Lateral IBIC – drift and diffusion

3 MeV proton beam X-Y scanning Cooling-heating BiasPreamplifierAmplifier ADC Digital oscilloscope DSO TRIBIC DAQ IBIC MAPS CdZnTe Au-contacts Temperature dependent lateral IBIC CdZnTe - temperature range K

(  ) e =(1.4)*10 -3 cm 2 /V (  ) h =1*10 -5 cm 2 /V (  ) e =(1.4)*10 -3 cm 2 /V (  ) h =1*10 -5 cm 2 /V IBIC line scan (anode to cathode) for CCE=100% Temperature dependent lateral IBIC CdZnTe

Radiation hardness tests - 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 beam induced damage: 50 Li 7  m -2 = 5×10 9 cm -2 6 Li 7  m -2 = 6×10 8 cm -2 (4 events per pixel) IBIC on-line monitoring:

Irradiation pattern (3 x3 quadrants, 50 x 50 pixels, 100 x 100  m 2 each, 20  m gaps, t irrad = 5 min. – 3 h ) Radiation hardness tests - damage done with He, Li, O & Cl ions of similar range Si diode

Radiation hardness tests Modeling of CCE: - doping profiles & el. field (CV) - drift velocity profiles (el. field) - hole contribution negligible - vacancy profile (SRIM) - predominantly divacancies (DLTS) - dE/dx from (SRIM) - electron lifetime: k  = 0.88 * k = 0.18 !! 18% of radiation induced defects leads to stable divacancies ! effective fluence Si diode

Question: how to calculate the energy levels of produced traps? Answer: DLTS, but what if.....a) number of traps is very very large? b) I want good spatial resolution? c) my sample is diamod? Radiation produces lattice defectsel. active traps, CCE<100%

Question: how to calculate the energy levels of produced traps? Answer: DLTS, but what if.....a) number of traps is very very large? b) I want good spatial resolution? c) my sample is diamod? Ion Induced DLTS Steps: - IBIC with MeV ions, charge carriers will fill traps - record cumulative collected charge in time using charge sensitive preamp and digital scope at different temperatures - choose rate windows like in conventional DLTS - plot Q(t 2 )-Q(t 1 ) vs. T - make Arrhenius analysis and get activation energy of the defect Radiation produces lattice defectsel. active traps, CCE<100%

6H-SiC diode - irradiation with 1 MeV electrons,el. active traps, CCE<100% - IBIC with MeV alphas cumulative collected charge 250K<T<320 K Q(t 2 )-Q(t 1 ) vs. T Estimated activation energy: IIDLTS DLTS 0.50±0.05 eV 0.53±0.07 eV N. Iwamoto et al., IEEE TNS, 2011

C. Canali, E. Gatti, S.F. Koslov, P.F. Manfredi, C. Manfredotti, F. Nava, A. Quirini Nucl. Instr. Meth. 160 (1979) (transient current technique, TCT) - use of current sensitive amplifier instead of charge sensitive - high frequency oscilloscope, - novel technique ??? 400 μm thick natural diamond

- 2 GHz, 40 dB, 200ps rise time amplifier (CIVIDEC) - broad-band 3GHz scope (LeCroy) TCT on scCVD diamond at low temperatures H. Jansen (CERN), CARAT Workshop, GSI, 2011

Lower fields are required to reach saturation velocity at low tempertures Saturation velocity H. Jansen (CERN), CARAT Workshop, GSI, 2011

Plasma effects

Significantely higher charge trapping at low temperatures !! Charge trapping/detrapping H. Jansen (CERN), CARAT Workshop, GSI, 2011

Detrapping (~ 10 ns) Charge trapping/detrapping H. Jansen (CERN), CARAT Workshop, GSI, 2011

Position sensitivity - scCVD diamond, 500 μm thick - lateral scan with 4.5 MEV p - (μτ) e < (μτ) h - 6 GHz, 15dB preamp (Minicircuits) - 5 GHz, 10 GS/s scope (LeCroy) 0 500μm Achievable resolution ≈ 10 μm 500 μm thick scCVD diamond