1 Annealing studies of Mimosa19 & radiation hardness studies of Mimosa26 Dennis Doering* 1, Samir...

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Annealing studies of Mimosa19& radiation hardness studies of Mimosa26

Dennis Doering*1, Samir Amar-Youcef 1,3,Michael Deveaux1, Melissa Domachowski1, Ingo Fröhlich1, Christian Müntz1, Sarah Ottersbach1, Joachim Stroth1, Franz M. Wagner2 for the CBM-MVD-Collaboration

1 Goethe University Frankfurt am Main, 2 TU München, Forschungsquelle Heinz Maier-Leibnitz (FRM II), 3 Helmholtz Research School, Frankfurt

*[email protected]

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Outline- MAPS, radiation damage and annealing- Leakage current and annealing- Charge spectrum and annealing- Radiation hardness study of Mimosa26- Summary

*[email protected]

/23

Annealing studies with combined radiation irradiated MAPS

3Motivation

The CBM-experiment (at FAIR)

The CBMMicro Vertex Detectorbased on MAPS

Expected radiation dose per CBM running-year:

How can a sensor chip tolerate such radiation doses?Þ Annealing & partially depleted Mimosa26?

Dennis Doering CBM Coll Meeting

GSI 2010

/23Operation principle of MAPS


4

Reset+3.3V+3.3V

Output

SiO2 SiO2 SiO2

N++ N++N+ P+

P-

P+

Diode

Epitaxial Layer

P-Well

Substrate


GSI 2010

/23


5Operation principle of MAPS

Reset+3.3V+3.3V

Output

SiO2 SiO2 SiO2

N++ N++N+ P+

P-

P+

Diode

Epitaxial Layer e-


GSI 2010

/23


6Operation principle of MAPS

Reset+3.3V+3.3V

Output

SiO2 SiO2 SiO2

N++ N++N+ P+

P-

P+

Diode

Epitaxial Layer e-


GSI 2010

/23


7Types of radiation damage

To be investigated and improved: Radiation hardness against…

… ionizing radiation:• Caused by charged particles and photons • Energy deposited into the electron cloud• Can ionize atoms and destroy molecules• Can be studied with X-ray radiation

… non-ionizing radiation:• Caused by heavy, charged and neutral,

particles• Energy deposited into the crystal lattice• Atoms are displaced• Can be studied with fast neutron radiation

Farnan I, HM Cho, WJ Weber, 2007. "Quantification of Actinide α-Radiation Damage in Minerals and Ceramics." Nature 445(7124):190-193.


GSI 2010

/23


8Radiation tolerance against radiation

Reset+3.3V+3.3V

Output

SiO2

N++ N++N+ P+

P-

P+

SiO2

Defects generated by non-ionizing radiation.


GSI 2010

/23


9Radiation tolerance against radiation

Reset+3.3V+3.3V

Output

SiO2

N++ N++N+ P+

P-

P+

SiO2Positive Charge

Positive charge generated by ionizing radiation.


GSI 2010

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10Leakage current

Reset+3.3V+3.3V

Output

SiO2

N++ N++N+ P+

P-

P+

SiO2Positive Charge

--

-

--

- --

Leakage current caused by radiation induced defects is collected.


GSI 2010

/23


11Annealing

Reset+3.3V+3.3V

Output

N++ N++N+ P+

P-

P+

SiO2Reduced positive Charge

Beneficial annealing: Interstitial atoms and vacancies recombine.Reversed annealing: Several defects form stable clusters.

Leakage current may increase or decrease due to annealing.

Annealing of defects

Clusterformation Recombination


GSI 2010

/23


12Sensors and irradiation

Used chips: Mimosa19 developed by IPHC Strasbourg.

Fast reactor neutrons: +(~100kRad γ) → Mostly non-ionizing radiation damage as sensors are not powered.~10keV X-rays (200kRad): only ionizing radiation damage.

Combined radiation: ;1 year room temperature annealing; 200kRad X-rays.

Neutron radiation performed by F. Wagner at FRM II Munich.X-ray radiation performed by A. Dierlamm at KIT.

Mimosa19


GSI 2010

Joachim Stroth

Hier sollten die bestrahlungsdosen angegeben werden. Auch details ueber die Bestrahlung!

/23


13Temperature profile

T[°C]

Time

20°C

80°C

Neutronradiation

1 year

X-rayradiation

Measurementsat T=20°C (280h)

Heating at T=80°C (73h)

Measurements and storage at T=20°C (191h)

2h transport


GSI 2010

Joachim Stroth

Hier sollten die bestrahlungsdosen angegeben werden. Auch details ueber die Bestrahlung!

/23Annealing at room temperature


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0 40 80 120 160 200 240 280300

350

400

450 X-ray radiation combined radiation

Leak

age

curr

ent [fA

]

Anneal time at T=20°C [h]Beneficial annealing at T=20°C decreases leakage current by 20%.No reverse annealing observed.

-20%


GSI 2010

/23

0 40 80 120 160 200 240 280 320 3600

50

100

150

200

250

300

350

400

450

irradiated with X-ray combined neutron no

radiationLeak

age

curr

ent [fA

]

Net anneal time [h]

T=20°C T=80°C

-70%

Annealing at T=20°C and T=80°C


GSI 2010


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Leakage current decreases by ~70% after beneficial annealing at T=20°C and T=80°C.Neutron irradiated sensors exhibits no significant annealing, neither beneficial nor reverse.No reverse annealing observed for up to 70h at T=80°C.

/23Spectrum before and after X-ray radiation


GSI 2010


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0 100 200 300 400 500 6000

100

200

300

400

500

600

700

800

Before radiation After radiation

Ent

ries

in h

isto

gram

Charge collected [ADC]

X-ray irradiation shifted the spectrum to lower values.

Calibration peak

Cd-109-source

/23Spectrum after annealing


GSI 2010


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0 50 100 150 200 250 300 350 400 450 500 550 600 6500

100

200

300

400

500

600

700

800

Before radiation After annealing

Ent

ries

in h

isto

gram


Annealing recovers the shift of the spectrum.

Calibration peak

Cd-109-source

/23Calibration peak and annealing


GSI 2010


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0 5 10 15 20520

530

540

550

560

570

580

590

600

610

620

T=80°C

Posi

tion o

f calib

ratio

n p

eak

[AD

C]

Number of measurements

X-ray radiation Combined radiation

X-r

ay

radia

tion T=20°C

The position of the calibration peak is recovered. Not completely recovered after combined radiation.Þ combined radiation damage effect?

Cd-109-source

/23Mimosa26


GSI 2010

Radiation hardness studies of Mimosa26

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Analog output

digital output

pixel array:1152 columns*576 rowspitch 18.4 µm

More details: Talk C.Schrader

Two versions: Standard and partially depleted

/23Partially depleted Mimosa26

+3.3VOutput

SiO2 SiO2

N++

N+SiO2 SiO2

P++ P++ P++

GND GND

+3.3V

E


GSI 2010


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/23First analysis results


GSI 2010


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0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 300

5000

10000

15000

20000

25000Mimosa26

T=-20°C d=6 1012neq

/cm2

Entrie

s in

his

togra

m

Noise [e]

0 50 100 150 200 250 300 350 400 450 5000

100

200

300

400

500

600

700

800

900

Entrie

s in

his

togra

m


Mimosa26

T=-20°C d=6 1012neq

/cm2

55Fe: 4 pixel cluster spectrum

Mimosa26 Spectrum Mimosa26 Noise

First tests successfully performed at T= -20°C and .

Prelim

inary

/23Comparison standard and depleted sensor


GSI 2010


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0 50 100 150 200 250 300 350 400 450 500 550 600 6500

200

400

600

800

1000

1200

1400

1600

unirradiated

6 1012 neq

/cm²

Ent

ries

in h

isto

gram


Standard sensor Epitaxial layer: 14µm

0 50 100 150 200 250 300 350 400 450 500 550 600 6500

100

200

300

400

500

600

unirradiated

6 1012 neq/cm²

Ent

ries

in h

isto

gram


Depleted sensor 400 Epitaxial layer: 15µm

Fe-554 pixel clusterT=-20°C

Fe-55 4 pixel cluster T=-20°C

Peak of the standard sensor is shifted to lower energy. Peak of the depleted sensor is not shifted.The depleted sensor seems to be more radiation hard than the standard sensor, to be confirmed in beam tests (June 2010).

Shift afterirradiation No shift

/23


23Summary

Annealing- Systematic annealing studies on MAPS have been performed.- Annealing has been studied comparing individual (X-ray, neutron) with combined irradiation.- Beneficial annealing effects are observed for X-ray and combined irradiation.- Significant annealing effects for only neutron irradiation are not observed.- Reverse annealing effects have not been observed.- Annealing recovers the charge spectrum shift after X-ray radiation completely.

Mimosa26- Mimosa26 radiation hardness studies are started.- Depleted Mimosa26 seems to be more radiation hard than standard sensors.

Conclusion- Annealing seems to be a promising strategy to recover the radiation induced performance

losses in the MAPS-based vertex detectors like the MVD of CBM.

Thank you for your attention


GSI 2010

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Backup

/23Noise and Collection peak


GSI 2010


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Only depleted sensors

/23Calibration peak


GSI 2010


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Depleted

Standard

Vetotrigger: Only diode hits

/23

Time

UK

IReset

0

1

2

3

1. Reset transistor is opened refilling the capacity.

C

+3.3V

K

Resettransistor

Operation principle of the preamplifier

Dennis Doering CBM Coll Meeting GSI 2010


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Joachim Stroth

Das CDS ist lokal in der Zeit. Die Grafik ist meines Erachtens irreführend. Auch ist laut Grafik das CDS mit Signal kleiner als ohne! Warum ist der Ladestrom "exponentiell" und der Leckstron "linear"?Erklärung dauert wahrscheinlich lange!SONST SEHR SCHÖN

/23

Time

Time

UK

ILeakage

0

1

2

3

2

UF0

UF1C

+3.3V

K

Resettransistor

CDS= UF0- UF1

2. Leakage current lowers slightly the voltage. The voltage is measured twice and compared (CDS).




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Joachim Stroth


/23

Time

Time

UKIReset

0

1

2

3

CDS= UF0- UF1

2

UF0

UF1

3. Reset transistor is opened again refilling the capacity.

C

+3.3V

K

Resettransistor




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Joachim Stroth


/23

Time

Time

UK

K

IReset

ILeakage

particle

ISignal

0

1

2

3

2

UF0

UF1

UF0

UF1

4. A particle generates signal charge, which lowers the voltage and increases the CDS.

C

+3.3V

K

Resettransistor

CDS= UF0- UF1




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Joachim Stroth


/23

Time

Time

UK

0

1

2

3

2

UF0

UF1

UF0

UF1

UF0

UF1

5. During the next frame no particle, only leakage current is measured.

IReset

ILeakage

C

+3.3V

K

Resettransistor

CDS=UF0- UF1




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Joachim Stroth


/23

Time

K

1

2

2

Threshold

Hit identified!

Measurementof leakage currentVariation: Noise

6. A threshold is applied to identify a hit which might be generated by a particle.

CDS= UF0- UF1




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Joachim Stroth


/23Defect annealing


GSI 2010


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Defect migration Complex formation

Complex dissociation

Em

Ef

Ed

Em, Ef and Ed depends on temperature.=> Each defect has a activation temperature. So heating the sensor may transform the defects. Heating more activates more defects. In addition question of probability.

1 Annealing studies of Mimosa19 & radiation hardness studies of Mimosa26 Dennis Doering* 1, Samir...

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