Analysis of S002 scan data

Bart Bruyneel and Benedikt Birkenbach – IKP Cologne At the 7th AGATA week, Uppsala July. 2008

S003

ProcedureScan data:

•S003 scan @ liverpool

•Averaged by J. LjungvallSimulation (~20 parameters):

•Positions (offsets)

•Responses (Preamp + Xtalk)

•Mobility (e-, h+ and lattice)

•Fields (Space charge)

Comparison:

•FOM (Chi Square)

Repeat till parameters optimalRepeat till parameters optimal

Chi Square evaluationS002 S003

Azim. scans #evts avg. FOM #evts avg. FOM20mm 97 4.74E-02 69 8.68E-0224mm 262 4.08E-02 202 6.71E-0227mm 144 4.55E-02 120 7.42E-0231mm 204 5.37E-02 128 7.99E-02

Line scans1 119 8.28E-02 56 1.13E-012 84 7.07E-02 0 .---3 44 9.73E-02 4 3.54E-014 54 6.55E-02 57 1.30E-015 75 7.86E-02 42 7.68E-026 57 6.18E-02 47 6.92E-027 89 6.78E-02 0 .---8 78 5.20E-02 84 1.08E-019 46 6.18E-02 33 2.28E-01

10 48 5.67E-02 5 1.39E-0111 11 excluded 0 .---12 64 5.39E-02 39 1.23E-0113 61 7.47E-02 37 8.73E-0214 39 6.62E-02 34 1.93E-0115 57 6.16E-02 38 6.72E-0216 34 3.86E-02 9 1.19E-0117 43 8.78E-02 30 1.28E-0118 0 .--- 4 9.30E-02

total 1710 106 1038 110

> Almost 2x worse in Chi Square <??? Noise, derivative crosstalk, ... ???

Parameters in detail : a) Offsets

Position of crystal:

•X,Y position known from singles scan,

•Z position to be determined relative to collimators

90

100

110

120

130

140

150

160

170

180

190

20 25 30 35 40 45 50 55 60

Z offset [0,1 mm]

Ch

i sq

uar

e va

lue

nea

r m

inim

um Optimum S002: Zoffset = 3,86 mm

S003: Zoffset = 5,24 mm

• Variation of lattice orientation:

90

110

130

150

170

190

210

-200 -150 -100 -50 0 50 100 150 200

Position of <100> direction [degrees]

chi s

quar

e va

lue

arou

nd m

inim

um

S002 : <100> = -14,9º

S003 : <100> = 43.7º

S002 : <100> = -14,9ºS003 : <100> = 43.7º

A

F

B

E

D

C

Parameters in detail : b) Mobilities Electron Mobility:

Dir <100>[cm^2/Vs] E0 [V/cm] n [cm^2/Vs]

Miniball 12fold 38609 0.805 511 -171S002 37200 0.805 510 -167S003 39400 0.782 503 -1

Dir. <111> [cm^2/Vs] E0 [V/cm] n [cm^2/Vs]

Miniball 12fold 38536 0.641 538 510S002 32908 0.774 448 -133S003 32907 0.738 474 -121

intervalley scattering rate (Eref = 1200V/cm)

b 2nd orderMiniball 12fold 0.496 0.0296 (negligible)S002 0.459 0.0294 (5.4 10-5)S003 0.460 0.0129 0.0018

Hole Mobility

Dir <100>[cm^2/Vs] E0 [V/cm]

Miniball 12fold 61824 0.942 185S002 62380 0.727 181S003 62768 0.747 154

Dir. <111> [cm^2/Vs] E0 [V/cm]

Miniball 12fold 61215 0.662 182S002 62508 0.757 144S003 60375 0.732 175

0.00E+00

2.00E+06

4.00E+06

6.00E+06

8.00E+06

1.00E+07

1.20E+07

1.40E+07

1.60E+07

1.80E+07

100 1000 10000

Field strength E [V/cm]

Ele

ctro

n D

rift

Vel

oci

ty [

cm/s

]

12fold Miniball

S002

S003

<100>

<111>

0.00E+00

2.00E+06

4.00E+06

6.00E+06

8.00E+06

1.00E+07

1.20E+07

100 1000 10000

Field strength E [V/cm]

Ho

le D

rift

Ve

loc

ity [

cm

/s]

12fold Miniball <100>

S002 <100>

S003 <100>

12fold Miniball <111>

S002 <111>

S003 <111>

Electron mobility equal

Hole mobility unequal

Parameters in detail : c) Space Charge

Zoom:

Rather insensitive in certain regions.

Region > 0 is not physical

Region < -2 is not likely

<-2,0

-1,0 -0,1

-1,0

Core @

5000V

Unphysical90

95

100

105

110

115

120

125

130

-4 -3 -2 -1 0 1 2

Space charge [10^10 /cm^3] at corners - see insert

Chi

squ

are

valu

e ne

ar o

ptim

um

Space Charge [1010/cm3] •cylinder symmetry•Linear in r and z : 4 point fit

S002:

S003:

-3,0

-2,9 1,3

1,1

Core @

4000V

90

100

110

120

130

140

150

160

-4 -3 -2 -1 0 1 2

Space charge [10 1̂0 /cm 3̂] at corners

Ch

i sq

ua

re v

alu

e n

ea

r o

ptim

um

Unphysical

Unrealistic model for S003 !!!

Option: Space charge from capacity measurements

Capacities A001 @ 3500 V

0

0.5

1

1.5

2

2.5

Ring1 Ring2 Ring3 Ring4 Ring5 Ring6

Seg

men

t C

apac

ity

[p

F]

A

B

C

D

E

F

Capacities A001 @ 5000 V

0

0.5

1

1.5

2

2.5

Ring1 Ring2 Ring3 Ring4 Ring5 Ring6S

egm

ent

Cap

acit

y [p

F]

A

B

C

D

E

F

50% variation

Late depletion

“Capacitance-voltage profiling„

e.g. Review article: Semicond. Sci. Technol. 1 (1986) 7-27