Micron detector testing in Liverpool G. Casse – O. Lodge Laboratory, University of Liverpool

Micron detector testing in Liverpool

G. Casse – O. Lodge Laboratory, University of Liverpool

5/21/02 LHCb week G. Casse – O. Lodge lab. University of Liverpool


Outline:Irradiation of n-in-n and p-in-n 200 µm thick Phi-type detectors Test of distortion of the charge sharing ( function) in non-homogeneously irradiated n-in-n detectors Comparison with simulations Comparison of charge collection efficiency vs voltage curves obtained with beta particles (106Ru source) and 1060 nm laser Signal to noise with SCT128-VGComparison of CCE with n and p read out strips (n-in-n vs p-in-n diode geometry)



0

10

20

30

40

50

60

70

80

20 30 40 50 60 70 80

Position from Ref [mm]

Me

asu

red

flu

en

ce [

x10

13 c

m-2]

A n-in-n and a p-in-n phi detectors have been irradiated in the 24GeV/c CERN-PS beam area (Irrad1 zone). They were positioned to get a non-homogenous irradiation profile



The n-in-n phi-detector has been scanned using the fine spot 1060 nm laser in order to study the Neff profile and the function across the irradiated area. The manual x-y stage has a scale with 2µm step which allows the intermediate positioning with 1 µm precision. The light spot has a FWHM of about 7µm. The detector has been scanned near the outer region where the strip pitch is about 100µm. The metallisation on the backside of the detector has holes to avoid reflections of the laser light. The intermediate read-out strip screens the laser beam in the mid-strip area.



0

1E+12

2E+12

3E+12

4E+12

5E+12

6E+12

7E+12

8E+12

9E+12

0 100 200 300 400 500 600 700

Strip #

Neff

[cm

-3]

0

20

40

60

80

100

120

Vfd

[V]

The effective doping concentration as measured by the CCE curves in correspondence of laser illumination of different strips. The high gradient region is about from strip #550 to #600.



Scan across strips #517-#518

0

0.2

0.4

0.6

0.8

1

1.2

0 10 20 30 40 50 60 70 80 90 100Local position [µm]

Rig

ht

cha

rge

/To

tal

cha

rge

30 volt

50 volt

150 volt

300 volt


0

0.2

0.4

0.6

0.8

1

1.2


Rig

ht c

harg

e/To

tal c

harg

e

25 volt

70 volt

200 volt

Measurement of the function in differently irradiated area of the detector: “low gradient area (irradiation about at type inversion fluence)”




0

0.2

0.4

0.6

0.8

1

1.2


Rig

ht

char

ge

/To

tal

char

ge

40 volt

200 volt


0

0.2

0.4

0.6

0.8

1

1.2


Rig

ht c

harg

e/To

tal

char

ge

50 volt

150 volt

300 volt

Measurement of the function in differently irradiated area of the detector: “high gradient area”




0

0.2

0.4

0.6

0.8

1

1.2


Rig

ht

char

ge

/To

tal

char

ge

50 volt150 volt300 volt

Measurement of the function in differently irradiated area of the detector: “most irradiated area”



ISE simulation of the electric field (300 V applied bias) in the high gradient area of an irradiated (>4.1014 cm-2) p-in-n silicon detector and signal of two neighbour strips generated by a MIP crossing mid way of the two strips



ISE simulation of the electric field (120 V applied bias) in the high gradient area of an irradiated (>6.1014 cm-2) n-in-n silicon detector and signal of two neighbour strips generated by a MIP crossing mid way of the two strips. The difference in signal height corresponds to the one obtained by moving the impact point of the MIP off centre by half a micron.



Irradiated area (>5.1014 p cm-2)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 100 200 300 400 500 600Bias [V]

CCE Source (#99-102)

Laser (#101)

Irradiated area (~3.1014 cm-2)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 100 200 300 400 500Bias [V]

CC

E

Laser #60

Source 55-60

Comparison between CCE obtained with 1060 nm laser and 106Ru source



Preliminary comparison of CCE between n-in-n and p-in-n detectors: highly irradiated region. The signal was induced by 1060 nm laser. The detectors were irradiated together. Thickness of both types: 200 µm.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 100 200 300 400 500 600

Bias [V]

CC

E

p-in-n (High irradiation area)

n-in-n (high irradiation area)



Noise performances:

The measured S/N for b particle (106Ru) signal signal with SCT128VG for this detector is ~16 in the low irradiation region and ~13.5 in the higher irradiated region. The noise level is independent on the applied bias between 50 to 400 volts, as expected with irradiated silicon detectors. There is no evidence of microdischarge at any voltage. This results is preliminary: only 1/8 of the detector has been tested up to now.



Results with populated (12 chips) IDE hybrid and irradiated 200µm p-in-n detector

0

5

10

15

20

25

30

35

0 100 200 300 400 500

Bias [V]

No

ise

co

un

ts (

#)

Chip 4 (Irr. area)

Chip 5 (Irr. area)

Chip + fan-in noise

Microdischarge



Status of VELO hybrid support card (T. Smith)



Conclusions:

Distortion of the resolution due to non-homogeneous irradiation does not need correctionCCE with n-strip read-out superior at low voltages after irradiationNo evidence of microdischages up to 500 V in n-in-n (p-spray) detectors

Documents

Micron detector testing in Liverpool G. Casse – O. Lodge Laboratory, University of Liverpool