Elèni BerdermannGSI, GSI, HelmholtzHelmholtz ZentrumZentrum ffüürr SchwerionenforschungSchwerionenforschung

1st CARAT workshop, DEC_09 Early Diamond-on-Iridium (DoI) samples

Contributing to these studiesContributing to these studiesContributing to these studiesUNIVERSITY OF AUGSBURGGSI - DETECTOR LABORATORY

Stefan DunstStefan GsellMatthias SchreckChristian Stehl

Mircea CiobanuMD Shahinur RahmanCarmen SimonsMichael TrägerEBe

GSI – ACCELERATOR HFPeter Moritz

GSI – TARGET LABORATORYAnnett HübnerBirgit KindlerBettina LommelWilly Hartmann

CARAT –Advanced Diamond Detectors1st CARAT workshop, DEC 2009

OutlineOutlineOutline

Introduction

Bulk and surface structure

Electronic propertiesDark conductivity

Timing signals

Charge Collection Efficiency (CCE)

Homogeneity of the signal response

Summary and conclusions

1st CARAT workshop, DEC_09 Early Diamond-on-Iridium (DoI) samples

IntroductionIntroductionIntroduction

Motivation Radiation hard, ultra-fast, large-area diamond tracking and ToF sensors of better homogeneity than pcCVDD

RequirementsHomogeneous, high-mobility detector material

δx, δy ≈ 3 – 100 µm ; σToF ≤ 50 ps; SPR ≈ 107 – 108 ions/s

High charge-collection efficiency (CCE)good S/N ratio for relativistic light ions and protons

1st CARAT workshop, DEC_09 Early Diamond-on-Iridium (DoI) samples

DoI material(s) – Post processingDoIDoI material(smaterial(s) ) –– Post processingPost processingDia/IDia/Ir/r/YSZ/Si(001): (cube on cube)YSZ/Si(001): (cube on cube)

HI sensors

1) IRIDIUM ELECTRODE(growth side polished)

Contacts

Iridium substrates:4 inch wafers routinely realized

ORIGINAL STRUCTURE

DoI 549a, d = 230 µm

2) FREESTANDING(both sides polished)

Contacts

universalsamples

HVContacts

DoI 724b, d = 12 µm

3) ADDITIONALIR LAYER

ultra-thinlow-energy HI

sensorsM. Schreck et al, Uni Augsburg

1st CARAT workshop, DEC_09 Early Diamond-on-Iridium (DoI) samples

Bulk Structure⎝Birefringence imagingBulk StructureBulk Structure⎝⎝Birefringence imagingBirefringence imagingStefan Dunst, Uni Augsburg; Michael Träger, Carmen Simons, GSI (DL)

Dia-on-DiaDia-on-Iridium Dia-on-Silicon

‘quasi’single-crystal

poly-crystal single-crystal

1st CARAT workshop, DEC_09 Early Diamond-on-Iridium (DoI) samples

Surface structure ⎝ AFM imagingSurface structure Surface structure ⎝⎝ AFM imagingAFM imagingStefan Dunst, Uni Augsburg

Nucleation side

Growth side

DoIDoI 549a,549a,No add. N2,No add. N2,free standingfree standingD = 230 D = 230 µµmm

11 scaife polished

1st CARAT workshop, DEC_09 Early Diamond-on-Iridium (DoI) samples

Metallization by sputtering (Ti-Pt-Au)Metallization by sputtering (TiMetallization by sputtering (Ti--PtPt--Au)Au)

DoIDoI 724b 724b 22ndnd IrIr layer defining anlayer defining anactive thickness of 12active thickness of 12µµmm

2

4-sector electrodeon growth side

Bottom view on ‘1st’ Ir layer

B. Lommel, A. Hübner et al. GSI (TL)

1st CARAT workshop, DEC_09 Early Diamond-on-Iridium (DoI) samples

Electronic propertiesElectronic propertiesElectronic propertiesIV characteristics of the different CVDD types IV characteristics of the different CVDD types

(a) (b) (c)

Dia-on-Dia Dia-on-IridiumDia-on-Silicon

The lowest dark conductivity has been measured for Dia-on-Iridium.1st CARAT workshop, DEC_09 Early Diamond-on-Iridium (DoI) samples

Electronic properties - dark conductivity Electronic properties Electronic properties -- dark conductivity dark conductivity Dark conductivity studiesDark conductivity studieswith DoI549a

MD Shahinur Rahman, GSI MC PAD

with DoI549a

ACTIVATION ENERGY EacACTIVATION ENERGY ACTIVATION ENERGY EEacacIV (T) IV (T) -- DEPENDENCEDEPENDENCE

M. Pomorski PhD thesis: EEacacSC≈ 0.35 – 0.39 eV: B activation

1st CARAT workshop, DEC_09 Early Diamond-on-Iridium (DoI) samples

Electronic properties – dark conductivityElectronic properties Electronic properties –– dark conductivitydark conductivity

1st CARAT workshop, DEC_09 Early Diamond-on-Iridium (DoI) samples

CHECK OHMIC and SCL CONDUCTIONCHECK OHMIC and SCL CONDUCTION

Dark conductivity studiesDark conductivity studieswith DoI549a

MD Shahinur Rahman, GSI MC PAD

with DoI549a

α = 1 OHMICα ≥ 2 SCL

Electronic properties – dark conductivityElectronic properties Electronic properties –– dark conductivitydark conductivity

1st CARAT workshop, DEC_09 Early Diamond-on-Iridium (DoI) samples

MD Shahinur Rahman, GSI MC PAD

ECATJ .)ln()ln( *

2 +=b

d

kk

q

C..4 επ

=with SCHOTTKY BARRIER Φb

Dark conductivity studiesDark conductivity studieswith DoI549a with DoI549a

ΦΦbb = 1.8 = 1.8 --1.9 1.9 eVeV

Detector setup for a-ToF measurementsDetector Detector setupsetup forfor aa--ToFToF measurementsmeasurements

conductive rubber

main pcb back side

main pcb front side

No α-collimator in this case

DoI 724b

1st CARAT workshop, DEC_09 Early Diamond-on-Iridium (DoI) samples

241Am-α-induced transient current signals241241AmAm--αα--induced transient current signalsinduced transient current signals

Dia-on-Dia Dia-on-IridiumDia-on-Silicon

‘‘SINGLESINGLE--CARRIERCARRIER’’ DRIFT IN THE DRIFT IN THE ‘‘SMALLSMALL--SIGNALSIGNAL’’ CASECASE

The TC signals of DoI sensors show narrowest FWHM (< 500ps) and amplitudes (on 50Ω) comparable to homoepitaxial diamond.

1st CARAT workshop, DEC_09 Early Diamond-on-Iridium (DoI) samples

Timing signal characteristics – DoI 724bTiming signal characteristics Timing signal characteristics –– DoIDoI 724b724bα-source, DBAII, and +HV on growth side

16 µ

A ≈

100

mV

on 5

0Ω(a

t D

BA g

ain

122.

5)

1V/µm20mV/div 2V/µm20mV/div

HO

LE D

RIFT

SIG

NA

LS

4V/µm40mV/div3V/µm30mV/div

t-axis: 500ps/div1st CARAT workshop, DEC_09 Early Diamond-on-Iridium (DoI) samples

Timing signal characteristics – DoI724bTiming signal characteristics Timing signal characteristics –– DoI724bDoI724bα-source, DBAII, and - HV on growth side

16 µ

A ≈

100

mV

on 5

0Ω(a

t D

BA g

ain

122.

5)

-2V/µm40mV/div

-1V/µm30mV/div

ELEC

TRO

N D

RIFT

SIG

NA

LS

-4V/µm50mV/div-3V/µm50mV/div

t-axis: 500ps/div1st CARAT workshop, DEC_09 Early Diamond-on-Iridium (DoI) samples

Charge collection efficiency (CCE)Charge collection efficiency (CCE)Charge collection efficiency (CCE)

3α - line source

E [V/µm]-6 -4 -2 0 2 4 6

CC

E

-1.0

-0.5

0.0

0.5

1.0

DG PC_CVDD

AG PC_CVDD incr_neg Q1

incr_neg Q2

incr_neg Q3

incr_neg Q4

decr_neg Q1

decr_neg Q2

decr_neg Q3

decr_neg Q4

incr_pos Q1decr_pos Q1incr_pos Q2

incr_pos Q3

incr_pos Q4

decr_pos Q2

decr_pos Q3

decr_pos Q4

Stopped ions STRONG POLARIZATION

DoI724b12µmDoI549a

230µm

CARAT –Advanced Diamond Detectors1st CARAT workshop, DEC 2009

Homogeneity of the sensor responseHomogeneity of the sensor responseHomogeneity of the sensor response

DoI 724b @ -2V/µm

MEASURED α-ENERGY [keV]

0 500 1000 1500 2000 2500

CO

UN

TS

1

10

100 pulser

Q1Q2 Q3Q4

QC [fC]1.0 10.0 100.0

CO

UN

TS20

40

60

80

100

120

DoI CVDD; 230µm pcCVDD; 350µm

scCVDD; 50µm

Energy resolution (α’s): ‘Thin’ DoI δE/E ≤ 20%‘Thick’ DoI δE/E ≤ 40%

Poly CVDD δE/E >> 60%

CARAT –Advanced Diamond Detectors1st CARAT workshop, DEC 2009

Summary and conclusionsSummary and conclusionsSummary and conclusionsVery low dark conductivity; order of 10-13A at 4V/µm

High activation energy Eac = 1.6eVSchottky conduction

CCEα ≈ 40% Extremely fast timing signals; FWHM << 500ps; rt< 200ps

no really suitable electronics available forTiming α-amplitudes as high as of best single-crystalsEnergy resolution δE/E < 20%

NEXT STEPS NEXT STEPS Signal simulations and FEE developmentsSignal simulations and FEE developmentsHeavyHeavy--ion beam tests in spring 2010ion beam tests in spring 2010Preparation of tools and assembly techniquesPreparation of tools and assembly techniquesfor largefor large--area strip sensorsarea strip sensors

1st CARAT workshop, DEC 2009 CARAT –Advanced Diamond Detectors

MERRY CHRISTMAS and HAPPY NEW YEAR !!!MERRY CHRISTMAS and HAPPY NEW YEAR !!!

1st CARAT workshop, DEC 2009 CARAT –Advanced Diamond Detectors