23.01.2002 IEKP - Universität Karlsruhe (TH)

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Preliminary

Pinhole Studies (not final) Pinhole Studies (not final)

F. Hartmann

IEKP - Universität Karlsruhe (TH)

• Creation of defined number of pinholes per chip

• Increase of leakage current according to LHC years also defines the voltage over the dielectric

(with Rpoly= 1.8MOhm)

o Effect of pinholes on readout

o Gain vs. number of pinholes??

o Gain vs. leakage current (= years of LHC operation)

Conclusion

23.01.2002 IEKP - Universität Karlsruhe (TH)

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Power ConsumptionPower Consumption

0.0 5.0x1013 1.0x1014 1.5x1014 2.0x1014 2.5x1014 3.0x1014

0.0

50.0µ

100.0µ

150.0µ

200.0µ

250.0µ

300.0µ

350.0µ

400.0µ

Data (500mm sensors, ~5kWcm) Linear Fit Extrapolated value for 500mm sensor

at r=60cm

a(T=-10°C) = 1.2 10-18 A/cm

I /

V [

A/c

m3 ]

eq. Fluence [n/cm2]

60mA/cm3 Ileak(-10°C)= 270mA (W6b) 540µA (module) P(500V, -10°C)=135mW/sensor

P ~ UFD I ~ d2 d ~d3

23.01.2002 IEKP - Universität Karlsruhe (TH)

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SetupSetup

P+

Al

SiO2

DC

ACbond

Ichannel=Itot / #channel=Itot/1024

Vdrop=Istrip*Rpoly = Istrip*1.8MOhm

300µA/1024 *1.8MOhm= 0.5V

30µA=0.05V

...

Array of IR LED forcont. illumination increase in total currentwith standard reverse bias.

Bonding artificial pinholes on purpose!

23.01.2002 IEKP - Universität Karlsruhe (TH)

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Noise vs. leakage currentNoise vs. leakage currentVb=500V; Il=0.3µA Vb=500V; Il=30µA

Vb=500V; Il=300µA •Pinholes highly leakage current dependent

•Very difficult to tag at starting current level

23.01.2002 IEKP - Universität Karlsruhe (TH)

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Vb=500V; Il0.3µA

Vb=500V; Il 120µA

Vb=500V; Il 30µA

Vb=500V; Il 300µA

Pedestals vs. leakage current Pedestals vs. leakage current NO change NO change

23.01.2002 IEKP - Universität Karlsruhe (TH)

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Gain vs. leakage current (calibration) Gain vs. leakage current (calibration) (Vbias=500V)(Vbias=500V) (5&6 pinholes) (5&6 pinholes)

Il 0,3µA ph 330

Il 90µA ph 260Il 60µA ph 280

Il 30µA (Vdrop=0.05V) ph 300

Preliminary

p

pp

p

pp

23.01.2002 IEKP - Universität Karlsruhe (TH)

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Gain vs. leakage current (calibration) Gain vs. leakage current (calibration) (Vbias=500V)(Vbias=500V) (5&6 pinholes) (5&6 pinholes)

Il 150µA ph 255 Il 240µA ph 255

Il 300µA (0.5V) ph 255

Preliminary

No change in gain at leakage currents above 150µA (up to 300µA)

??

23.01.2002 IEKP - Universität Karlsruhe (TH)

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Calibration/GainCalibration/Gain

No pinholes

4 pinholes 3 pinholes

p p

Vbias=500V; Il 60µA (Vdrop=0.1V)

23.01.2002 IEKP - Universität Karlsruhe (TH)

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Common modeCommon mode

0 pinholes

10 pinholes

Vbias = 400VIl = 200µA

23.01.2002 IEKP - Universität Karlsruhe (TH)

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ConclusionConclusion

• We bonded up to 10 pinholes per chip and imposed a current of 300µA/modules (330nA/channel; Vdrop = 0.5V)

~ 5 years of LHC operaton.

• No saturation of chip seen; but final current level not yet reached. Only 300µA instead of 500-600µA

• Gain loss and change in common mode with increasing leakage current and number of pinholes

• Pinholes easy to tag with high current.

23.01.2002 IEKP - Universität Karlsruhe (TH)

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IV-Curve IV-Curve beforebefore//afterafter Irrad. Irrad.

23.01.2002 IEKP - Universität Karlsruhe (TH)

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