Surface measurements Surface measurements with ATLAS12A with ATLAS12A Matthew Domingo, Hartmut F.-W. Sadrozinski, Vitaliy Fadeyev Zachary Galloway, Zhijun LiangSCIPP, UCSC

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Electrical tests of ATLAS12A mini sensorsUCSC status Samples ◦ ATLAS12A samples irradiated with protons at Birmingham by 27MeV

protons ◦ Samples have not been annealed yet◦ 8 fluences : 1e12, 5e12,1e13,1e14,1e15,2e15,5e15 Neq/cm2 ◦ Zones : BZ3C and BZ3F

This talk focus on the following measurements◦R(interstrip)◦C(interstrip)◦PTP◦Implant sheet resistance

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Inter-strip capacitance Inter-strip capacitance C(interstrip) Measurements setups

BZ3C sensors , Measured in -10 °C , before annealed

◦ 5 probe methods: Middle strip connected to to LCR meters low side First neighbor strips connected to LCR meters high side. The Second neighbor strips grounded

◦ 3 probe methods: Similar to 5 probe methods Except that the 2nd neighbor strips are not

connected

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C(interstrip) C(interstrip) before before irradiation irradiation ATLAS07 and ATLAS12 have similar C(interstrip) 3 probe measurement are ~15% higher wrt 5 probe

methods due to second neighbor contribution

Voltage(V)

Frequency = 1MHz

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C(interstrip) [pF/cm]

Inter-strip capacitance VS Inter-strip capacitance VS frequencyfrequency Measured BZ3C sensors by 3 probe method at -10 °C

We test Frequency range from 50kHz to 2MHz. Low frequency region has a higher variance. Frequency dependence is reduced when Frequency >500kHz

Frequency [kHz]

Inter-strip capacitance ( pF/cm)

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Inter-strip capacitance ( pF/cm)

Frequency [kHz]

Bias Voltage dependence Bias Voltage dependence Inter-strip capacitance shows a stronger

voltage dependence at low frequency (i.e. 100kHz)

6Bias voltage(V) Bias voltage(V)

Inter-strip capacitance ( pF/cm) Inter-strip capacitance ( pF/cm)

100kHz

1MHz

Inter-strip capacitance VS Inter-strip capacitance VS FluenceFluenceMain result: Less impact by radiation in high frequency

region Inter-strip capacitance varied by 15% In high frequency region (>500kHz) for

most of samples One outliner varyied by 50% at Fluence =1e14.

Inter-strip capacitance In low frequency region (eg. 100kHz) is not stable Measured by 3 probe method with 300 V reserve bias at -10 °C

Inter-strip capacitance ( pF/cm)

Fluence [Neq/cm2]

100kHz1Mhz

Before irradiation

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Inter-strip resistance Inter-strip resistance The inter-strip resistance setup as follow

◦ BZ3C sensors ◦ Measured at -10 °C

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Measure nA current for GΩlevel resistanceRelative low S/NDo a careful job in grouding to reduce the noise

Inter-strip resistance VS Inter-strip resistance VS Fluence (Fluence (Φ)Φ)R(interstrip) drops significantly after

Φ>1e14 ◦Reduce from GΩlevel to MΩ level◦R(interstrip) /R(bias) <10, when Φ>2e15 ◦ATLAS Specification R(interstrip)

>10*R(bias)R(interstrip) (Ohm)

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Before irradiation R(interstrip) /R(bias)

Fluence [Neq/cm2]

Fluence [Neq/cm2]

PTP measurements PTP measurements Measure resistance of PTP structure vs.

voltage on implant (DC pad) Measure punch-through voltage after

irradiation Compare the different PTP structure

◦ Mainly the BZ3C and BZ3F

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BZ3C VS BZ3FBZ3C VS BZ3F BZ3C has a smaller punch-through voltage before radiation. After radiation, both sensors have similar punch-through voltage BZ3F have a higher asymptotic resistance

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before radiation Φ=5e15Resistance(Ohm)

Voltage (V) Voltage (V)

Resistance(Ohm)

resistance of PTP structure vs. resistance of PTP structure vs. voltage voltage

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As fluence increase◦ The resistance of PTP responses slower to

voltage ◦ punch-through voltage increased

BZ3C BZ3F

Resistance(Ohm) Resistance(Ohm)

Voltage (V)Voltage (V)

punch-through voltage VS punch-through voltage VS Fluence Fluence

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BZ3CBZ3F

Fluence [Neq/cm2]

Punch-through voltage (V)

Implant sheet resistance Measurement of sheet resistance of n-implant ATLAS specification: Implant resistance < 20

KΩ/cmMeasured resistance per strip ~ 19KΩ/cm

◦ Uniform in all the strips ◦ No dependence of bias voltage

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Implant resistance (KΩ/cm)

Strip numberBias voltage(V)

Implant resistance (KΩ/cm)

ATLAS12A VS ATLAS12A VS ATLAS12A ATLAS12A endcapendcap

The results of ATLAS12A compared to “ATLAS12” and “ATLAS12A endcap” See strong drop of R(interstip) with fluence increase as others sensors

R(interstip) Drop to MΩ level at Φ>2e15 in this result and Prague result (ATLAS12A EC) R(interstip) Drop to MΩ level at Φ>1e15 in Lancaster measurement(ATLAS12A)

See need to see higher frequencies for C(interstip) measurements At 100kHz, see larger Variation (>100%)

Larger than Lancaster result (ATLAS12A) (20%) and Prague result (ATLAS12A EC)“ (~50%)

At 1MHz, See similar variation (20%) with fluence as other measurements

“ATLAS12A endcap” results by Prague group: https://indico.cern.ch/event/312262/contribution/6/material/slides/0.pdf

ATLAS12 results by Lancaster: ◦ https://indico.cern.ch/event/292247/contribution/12/material/slides/1.pdf

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Summary Summary ATLAS12A mini sensors irradiated by protons are measured. Inter-strip capacitance in irradiated samples

◦ Increased by one order of magnitude at low frequency (100k)◦ Increased by 10~20 % at high frequency ◦ ATLAS Specification < 0.8 pF/cm at 100kHz

does not meet the specification at 100kHz When fluences >1e13 Very close to meet the Specification (0.8 pF/cm) at 1MHz

May revise the specification if the S/N is still large once we know ABCN130 performance

Inter-strip resistance ◦ ATLAS Specification R_INT>10*R(bias)◦ Accorinding to Specification interstrip resistance is not sufficient after fluences

>2e15 Neq/cm2

◦ After Φ>5e15, R_INT is about 0.3MOhm

◦ Still larger than the amplifier's input impedance (kOhm) PTP

◦ There is no defined acceptance criterion in ATLAS Specification ◦ BZ3C and BZ3F samples are measured. ◦ PTP performances are acceptable at all fluences

Implant resistance 19KΩ/cm, meet ATLAS specification (< 20 KΩ/cm) 16

Next steps Next steps Test BNL gamma radiated sensors

◦ Compare protons radiation VS gamma radiation damage

Starting on laser-based dynamic PTP study◦ Aim to report the results in next meeting

Will work on sensors performance after annealing,

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Backup Backup

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R(bias)

Fluence [Neq/cm2]

resistance of PTP structure vs. resistance of PTP structure vs. voltage voltage

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As fluence increase◦ The resistance of PTP responses slower to

voltage ◦ punch-through voltage increased

Backup: Bias Voltage Backup: Bias Voltage dependence dependence Inter-strip capacitance shows a stronger

voltage dependence at low frequency (i.e. 100kHz)

20Bias voltage(V) Bias voltage(V)

Inter-strip capacitance ( pF/cm) Inter-strip capacitance ( pF/cm)

100kHz

1MHz