+

Evaluation of Characteristics of Hamamatsu Low-Gain Avalanche Detectors

Sayaka Wada1, Kazuhiko Hara1, Kyoji Ohnaru1, Junki Suzuki1, Yoshinobu Unno2, Koji Nakamura2, Kazunori Hanagaki2, Yoichi Ikegami2,

Kazuhisa Yamamura3, Shintaro Kamada3, Yuhei Abo3, Hitomi Tokutake4, Daiki Yamamoto5

University of Tsukuba1, KEK2, HPK3, Tokyo Institute of Technology4, Osaka University5

Session11­3 HSTD11 at OIST, Japan

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

+Talk Outline

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

2

p Brief Introduction of LGAD

p Samples from HPK

p  IV/CV Measurements

p Charge Collection Measurements

p Summary

+ Introduction

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

3

Low Gain Avalanche Detectorp  Uniform high electric field @ N+-P+ junction (thin multiplication layer)

p  Avalanchep  Low Gain (~10) p  Optimum S/N for good timing (<50ps)p  Thinner detector possible

To realize 4D (even 5D) detectorgood for position and time measurements

P bulk

P+ Layer

Electric FieldP+ Electrode

Al

PInsulator

N+

+Hamamatsu LGAD

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

p Samples from HPKp  Monitor Diode

p  Chip Size: 2.5mm × 2.5mmp  Window 1mmφ

p  Stripp  Chip Size: 6.0mm × 12mmp  Strip Pitch: 80μm

p  Dose of P+ layerp  Low to high; A-B-C-D (HPK confidential)

p  Active thicknessp  50μm or 80μm

4

Monitor Diode Strip

SampleName

P+ DoseLight>dense

PhysicalThickness [μm]

ActiveThickness [μm]

50A A

150

5050B B50C C50D D80A A

8080B B80C C80D D

+Monitor Diode IV

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

5

p Leakage (LED OFF) ~nA

p  IR LED response (LED ON­OFF)p  Gain

p  More P+ dose, Lower Voltagep  Jumps @ ~30V

p  Breakdown Voltagep  80μm is higher than 50μmp  More P+ dose, Lower Voltage

p  Dose of P+ layerp  A, B: too weak?p  C, D: good

p  Active thicknessp  50μm looks better than 80μm

0 100 200 300 400 500 600 700 80011−10

10−10

9−10

8−10

7−10

6−10

5−10

0 100 200 300 400 500 600 700 80011−10

10−10

9−10

8−10

7−10

6−10

5−10

IR-LED ON-OFF

Leakage (LED OFF)

D C

D C B A

Curr

ent [

A]Cu

rren

t [A]

­Voltage [V]

@20℃

Active thickness50μm

Active thickness80μm

+Wavelength Dep. of IV Curve 6

-Voltage [V]0 10 20 30 40 50 60 70 80 90 100

Cur

rent

[A]

8−10

8−10×2

8−10×3

8−10×4

8−10×5

8−10×68−10×7

7−10

Infra-red GreenRed Blue

-Voltage [V]0 10 20 30 40 50 60 70 80 90 100

Cur

rent

[A]

8−10

8−10×2

8−10×3

8−10×4

8−10×5

8−10×68−10×7

7−10

Infra-red GreenRed Blue

〜〜Absorption Depth

0.5/ 2.0/ 3.0/ 20 μm

@20℃

Wave Length 464/ 565/ 627/ 850 nm

-Voltage [V]0 100 200 300 400 500 600

Cur

rent

[A]

10−10

9−10

8−10

7−10

6−10

5−10 Infra-redRedGreenBlueLeakage

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

80D80A 80D

p 0〜500Vp  Curves normalized @10Vp  Longer W.L., larger currentp  Breakdown Voltage has no W.L. dep.

p 0〜100Vp  Curves normalized @10Vp  More P+-region dose & Longer W.L., Larger Currentp  More P+-region dose, Higher Voltage @ ends of jumps

+

〜〜0 10 20 30 40 50 60 70 80 90 1000

0.20.40.60.81

1.21.41.61.82

9−10×

80A

80B

80C

80D

0 100 200 300 400 500 600 700 80011−10

10−10

9−10

8−10

80A

80B

80C

80D

Bulk Capacitance

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

7

p VFD in agreement with IV (25-35V)

p Depletion Stepsp  1st. Depletion: side regionp  2nd. Depletion: multiplication layer

p  More P+ dose, Higher depletion voltagep  3rd. Depletion: bulk

p 2nd. depletion voltage depends on the dose of P+ layer

Capa

cita

nce[

F]

­Voltage [V]

Capa

cita

nce[

F]

@1500Hz

­Voltage [V]

Active thickness80μm

Active thickness80μm

+ IV after γ-ray Irradiation

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

8

p 24 Nov. ­ 20 Dec. 2016 @ QST, Japanp  0.1/1.0/2.5 MGy

p Leakage increase but no P+ dose dep.p  γ-ray make only surface damage

p Gain retains

0 100 200 300 400 500 600 700 80010−10

9−10

8−10

7−10

6−10

5−10

0 100 200 300 400 500 600 700 80010−10

9−10

8−10

7−10

6−10

5−10

­Voltage [V]

Curr

ent [

A]

Curr

ent [

A]

IR-LED ON-OFF

Leakage(LED OFF)

Non-irrad.

γ-irrad.

Non-irrad.

γ-irrad.

0

2.5

@-20℃

Monitor Diode50D

Monitor Diode80D

+ IV after Neutron Irradiation

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

9

p 15 Dec. 2016 @ Ljubljana, Sloveniap  0.3/1.0/3.0 ×1015 1-MeV neq/cm2

p  After 60℃-80min. annealing

p Gain dropsp  Requires higher voltage (depends on fluence)p  e.g. 50D (280V→700V) Gain~5

0 100 200 300 400 500 600 700 8008−10

7−10

6−10

5−10

­Voltage [V]

Curr

ent [

A] Non-irrad.

Neutron-irrad.

IR-LED ON-OFF0 100 200 300 400 500 600 700 8008−10

7−10

6−10

5−10

­Voltage [V]

Curr

ent [

A]

1.0×1015 1-MeV neq/cm2

IR-LED ON-OFF

B

CD

high

low50μm

80μm

0.3

1.0

3.0

@-20℃

Monitor Diode50D

+Charge Collection Setup

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

10

p Gain evaluation by charge collectionp  Alibava: System using analog readout ASIC (Beetle) for LHCbp  IR-Laser (λ=1064nm) uniformly generate h-e pairs, mimicking charged particle traversing the sensor. (spot size: 2μm×2μm)

PC�

Alibava Mother Board �

Alibava Daughter Board �

XY Stage �

HV for Sensor�

Sensor�

50 ��

Trigger Pulse 10~20 ns�

Laser

Interstrip Center

+

Charge [ADC counts]0 100 200 300 400 500 600

Even

ts /

1 co

unt

0100200300400500600700800900

1000

Non irradiated

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

11

p  Gain stays constant (interstrip region)p  Gain increases (center in doped region)

>50Vp  Evaluation of gain:

    ADC (center @V)    ADC (interstrip@100V)

Charge [ADC counts]0 100 200 300 400 500 600

Even

ts /

1 co

unt

0100200300400500600700800900

1000

Center

50-200V

50V

100V 150V 200V

Interstrip

0 50 100 150 200 250 300 350 4000

5

10

15

20

25

30

35

40

Gain (V) =

­Voltage [V]

Gain

@20℃

50D

50D50D

+

Charge [ADC counts]0 100 200 300 400 500 600

Even

ts /

1 co

unt

0100200300400500600700800900

1000Charge [ADC counts]

0 100 200 300 400 500 600

Even

ts /

1 co

unt

0100200300400500600700800900

1000

Gain after Proton irradiation

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

12

p 2017.02.20~ @CYRICp  1.0×1015 1-MeV neq/cm2 p  After 60℃-80min. annealing

p Gain appears (interstrip)p  High voltage applicable after

irradiation

p Higher voltage required to retain same gain

100V 500V 600V 650V

100V 500V

600V

650V

@­20℃

­Voltage [V]0 100 200 300 400 500 600 700012345678910

Gain Non-irrad.

Center

Proton-irrad.Center

interstrip

50D

50DInterstrip

Center50D

+

40− 30− 20− 10− 0 10 20 30 40012345678910

Gain Uniformity

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

13

p Non irradiatedp  Uniformity dependent on bias

(require certain bias)

p After irradiationp  Uniformity seems improved

- Need more study[μm]

Gain

〜〜

250V

200V

100V

40− 30− 20− 10− 0 10 20 30 40012345678910

[μm]

Gain

700V

300V

Non irradiated

After Proton irradiation3.0 ×1015 1-MeV neq/cm2

50C

50D

+Summary

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

14

p We evaluated characteristics of HPK LGAD samplesp  Gain shows at ~30V (non irrad.)p  Gain retains after γ-ray irradiation (2.5MGy)p  After neutron irradiation, gain drops (1.0×1015 1-MeV neq/cm2 )

p We evaluated gain by charge collectionp  (Interstrip) Gain appears after irradiation due to high voltage (~500V)p  (Center) Gain drops after proton irradiation, needs higher voltagep  Irradiation seems improve gain uniformity

p Acknowledgement

+Backup Slides

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017 15

+M.D. IV Measurements Setup

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

16

p Response to LEDs with various wavelengthp  Blue (λ=464nm, D=0.5μm)p  Green (λ=565nm, D=2μm)p  Red (λ=627nm, D=3μm)p  Infrared (λ=850nm, D=20μm)

Wavelength [nm]200 300 400 500 600 700 800 900 1000

Abso

rptio

n D

epth

[m]

9−10

8−10

7−10

6−10

5−10

4−10

3−10

+

-Voltage [V]0 100 200 300 400 500 600 700 800

Cur

rent

[A]

8−10

7−10

6−10

5−1050DPixel

Temperature Dep. of IV

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

17

p Lower temperature, higher gainp  Because…

p  longer mean free pathp  higher acceleration energyp  higher impact ionization energy

-Voltage [V]0 100 200 300 400 500 600 700 800

Cur

rent

[A]

8−10

7−10

6−10

5−1080DPixel

0℃

60℃

60℃

Monitor Diode50D 0℃

Monitor Diode80D

+CC after Proton irradiation

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

18

p 2017.02.20~ @CYRICp  1.0×1015 1-MeV neq/cm2 p  After 60℃-80min. annealing

p Appear gain between stripsp  P dose of bulk increase because of

bulk damage by proton irradiation

p Higher gain retain under the stripp  appear at higher voltage

p Two type of electrode shapep  Type A: Simplep  Type B: more stable electric fieldp  detail (confidential to HPK)

Charge [ADC counts]0 100 200 300 400 500 600

Even

ts /

1 co

unt

0

200

400

600

800

1000

1200

1400

Charge [ADC counts]0 100 200 300 400 500 600

Even

ts /

1 co

unt

0

200

400

600

800

1000

1200

1400 Under the strip

100V 500V

600V 700V 730V

Between strips 100V

500V

600V 700V

730V

Type B 50D

Type B 50D

@-20℃

+Non irradiated sample

Sayaka Wada  HSTD11 at OIST, Japan  14 Dec. 2017

19

p  Same value @low voltage(<100V)p  increase C.C. under the strip @high

voltagep  Evaluation of gain @each voltage:

    ADC (under the strip)    ADC (between the strips)

Charge [ADC counts]0 100 200 300 400 500 600

Even

ts /

1 co

unt

0500

100015002000250030003500400045005000

Charge [ADC counts]0 100 200 300 400 500 600

Even

ts /

1 co

unt

0500

100015002000250030003500400045005000

Under the strip

10-380V

10-100V

150V

200V 250V

300V 350V 380V

Between the strips

0 50 100 150 200 250 300 350 400 450 5000

5

10

15

20

25

30

35

40

Type B 50D

Gain =

­Voltage [V]

Gain

Type B 50D

@20℃