An in-depth study of the I-LGAD sensor...2018/02/19 · An in-depth study of the I-LGAD sensor...

An in-depth study of the I-LGAD sensor

Iván Vila Álvarez.

Instituto de Física de Cantabria (CSIC-UC)

13th Trento Workshop

MPP, Munich, February 20th, 2018

The Team

2 Ivan Vila - 13th Trento Meeting, MPP, Munich 2018

E. Currás, J. Duarte, M. Fernández, A. García, G. Gómez, J. González, R. Jaramillo, D. Moya,

R. Palomo(1), I. Vila.

Instituto de Física de Cantabria(CSIC-UC) (1) Universidad de Sevilla

M. Moll, M. Centis Vignale, S. Otero Ugobono.

CERN

M. Carulla, D. Flores, S. Hidalgo, A. Merlos, G. Pellegrini, D. Quirion.

IMB-CNM (CSIC)

Developed inside the RD50 collaboration & AIDA -2020 WP7 on Advanced Hybrid Detectors.

Outline

— I-LGAD basics

— Gain spatial uniformity (fill factor)

— Tracking performance

— Timing performance

— Conclusions and outlook

Ivan Vila - 13th Trento Meeting, MPP, Munich 2018 3

I-LGAD basics: a 4th dimensional tracking sensor

Ivan Vila - 13th Trento Meeting, MPP, Munich 2018

Multiplication layer divided into strip Multiplication layer extended over the electrode Collects negative carriers (e) Collects positive carriers (h) Simple single side process Complex double side process

I-LG

AD b

asics

4

I-LGAD basics: multiplication footprint

— Distinct signature of signal amplification: cathode illumination with red laser

— Injections of electron into the cathode, resulting transient current is a sequential contribution of primary electrons reaching the amplification layer and secondary holes drifting towards the anode.


Cu

rren

t (a

.u)

Primary electrons current

Secondary holes

current

Multiplication onset

PAD-like LGAD Strip-like I-LGAD

I-LG

AD b

asics

Gain Spatial Uniformity: the fill factor issue — Conventional LGAD: multiplication layer interspace presents

reduced/suppressed gain.


I-LG

AD f

ill fac

tor

— I-LGAD: non-segmented multiplication layer should present uniform gain.

Gain Spatial Uniformity: Validation with MIPs


I-LG

AD f

ill fac

tor

AIDA-2020 WP7 Setup AKA as Atlas ITK setup (2016, 2017)

7

Strip LGAD

I-LGAD (8533W1K05T, 45 strips 160 um, non-irradiated)


Gain Spatial Uniformity: Collected Charge

I-LG

AD f

ill fac

tor

0

20

40

60

80

100

0 100 200 300 400 500

Carga en función del voltaje

Test Beam 2017

Test Beam

Q / k

e-

V / V

0

10

20

30

40

50

60

70

80

80 100 120 140 160 180 200 220

Charge dependence with voltage

for a LGAD at Test Beam

Q(Peak 1) / ke-Q(Peak 2) / ke-

Q / k

e-

V / V

LGAD

i-LGAD

Standard PIN

Gain Spatial Uniformity: Gain vs. Hit position (1) — Dependence of the Signal-to-Noise Ratio with the “fractional

position” for cluster of size two.


I-LG

AD f

ill fac

tor


Gain Spatial Uniformity: Gain vs. Hit position (2)

LGAD Strip

i-LGAD Strip

100 Volt bias

400 Volt bias

Artifact due to front-end saturation

30

43

I-LG

AD f

ill fac

tor

Tracking performance: Reference strip sensor

— Challenges: _ Difficult synchronization between Alibava daq (x3) and Eudaq.

_ Saturation of the Alibava ADC.


I-LG

AD t

rack

iing

Tracking performance: I-LGAD strip sensor

— Hit resolution biased by saturation of the Alibava ADC ?


I-LG

AD t

rack

iing

STANDARD

I-LGAD

I-LGAD

STANDARD I-LGAD

Set-up for timing characterization and DUT

— Time standard: constant time interval between two picosecond IR laser pulses (1060 nm)

— Fixed time interval between laser pulses generated by optical splitting and delayed recombination of a single laser pulse.


Laser diode Isolator Splitter

Delay Line Combiner DUT

45 strips Pitch 160 mm

I-LG

AD T

imin

g

13

Set-up for timing characterization and DUT (2)

— Signal amplified (60db, miteq 1660) & digitized (20Gs)

— Acquired averaged waveform from I-LGAD with a time interval of 52.23 ns between pulses.

I-LG

AD T

imin

g


Parameter extraction of the waveform.


— Single-shot (non-averaged) superposition of signals

— For each shot measured: Rise time, Signal amplitude and noise.

— Signal estimation as the charge under the transient waveform

— Noise estimation as the RMS of charge ( from the first 20ns of the waveform)

20 ns SNR ≡𝑺𝒊𝒈𝒏𝒂𝒍 𝑪𝒉𝒂𝒓𝒈𝒆

𝝈

𝝈 ≡ 𝑹𝑴𝑺 (𝑪𝒉𝒂𝒓𝒈𝒆 𝒃𝒂𝒔𝒆𝒍𝒊𝒏𝒆)

Waveform section from where the baseline noise is estimated I-LG

AD T

imin

g

15

Range for computing the pulse charge

I-LGAD Timing error estimation

— For each Bias voltage five thousand waveform acquired.

— The timing error σDt estimated from the width (sigma) of the distribution of the measured time intervals (Dt)

— Assuming timing errors similar for both pulses then σt for I-LGAD is given by σDt / √2 (quadratic sum of errors)


Vbias [V]

Rise Time

1 [ps]

Rise Time

2 [ps]

Vp1 [V]

Vp2 [V]

σbaseline [au]

SNR1

SNR2 Charge 1 [u. a.]

Charge 2 [u. a.]

Dt [ns]

σDt/√2 [ps]

700 334 357 1.105 1.034 13.5 20.6 19.41 279.0 262.0 52.23 25.45

600 326 327 0.965 0.905 14.8 17.02 15.99 252.0 236.6 52.23 26.87

500 330 327 0.815 0.762 14.8 16.0 14.97 237.0 221.6 52.23 27.58

400 357 353 0.677 0.631 14.4 14.3 13.34 206.0 192.1 52.23 31.82

300 357 355 0.526 0.496 15.1 11.5 10.77 174.8 162.6 52.23 37.48

200 354 358 0.370 0.347 14.6 9.5 8.63 139.0 126.0 52.23 46.67

16

Time error dependence with the SNR


I-LG

AD T

imin

g

Expected time error dependence with SNR

σt ∝rise time

SNR

Defining the effective SNR as

𝑆𝑁𝑅𝑒𝑓𝑓 ≡ 𝑆𝑁𝑅1𝑆𝑁𝑅2 𝑆𝑁𝑅12 + 𝑆𝑁𝑅2

2

σΔt2 = σt1

2 + σt22 σ∆t ∝

1

𝑆𝑁𝑅𝑒𝑓𝑓

σ∆t/

2 [𝑛𝑠]

1/𝑆𝑁𝑅𝑒𝑓𝑓

47 ps @ SNR ≅ 10

25 ps @ SNR ≅ 20

17

Summary and Outlook

— In-depth characterization of p-in-p LGAD (I-LGAD): fill factor, tracking & timing.

— Very promising candidate to become a true 4th dimensional tracking technology.

— Medium term activities:

_ Testing: Timing spatial uniformity.

_ Manufacturing: Thin-sensors (AIDA-2020), different segmented geometries.

_ Radiation tolerance (both to dose and displacement)…


… a particular case concerning radiation tolerance.

— The layout of the proposed LHC timing detectors: a mosaic of mini-pads (elements with area of few mm2)

— A pad-like LGAD is also a pad-like I-LGAD therefore they exhibit the same radiation tolerance


285 um

LGAD

I-LGAD

THANK YOU FOR YOUR ATTENTION


An in-depth study of the I-LGAD sensor...2018/02/19 · An in-depth study of the I-LGAD sensor...

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