Department of Chemistry, University of Helsinki, Finland METOREX International Oy, Espoo, Finland...

Department of Chemistry, University of Helsinki, Finland METOREX International Oy, Espoo, Finland

Characterisation of TlBr Crystals for

Detector Applications

V. Kozlov, M. Leskelä and H. Sipilä


IWORID2004


Detector properties

• Crystal quality

• Purity (composition)

• Previous study* => Chemical aspects• Crystal growth

• Purification

• * V. Kozlov, M. Leskelä, T. Prohaska, G. Schultheis, G. Stingeder and H. Sipilä, Nucl. Instr. and Meth. A (2004) (in press)


This study => Crystal quality

• Crystal growth

• Annealing (+hydrothermal)

• Methods:• X-ray rocking curve

• IV & photo-current

• X-ray Cu-radiation

• Polarisation microscope


Sample production from the ingot and wafer mapping

• Wafers and, then, slices were cut as is presented in Figure

Sohkl

• Two large crystals of diameter 21 mm were grown using Bridgman method

•<= Reference surface: plane (100) or (111)


Rocking curve mapping

1 3 (1 ) m a x -s

M 1 3 ( 1 ) 4 ( 1 ) S e t 2 2

M 1 3 (1 ) 4M 1 3 ( 1 ) 3 ( 3 ) S e t 4 5 M 1 3 ( 1 ) 3 ( 2 ) S e t 4 5 n e w

M 1 3 (1 ) 3M 1 3 ( 1 ) 2 ( 3 ) M 1 3 ( 1 ) 2 ( 1 ) S e t 6 7

M 1 3 (1 ) 2M 1 3 ( 1 ) 1 ( 2 ) s e t 0 0

M 1 3 (1 ) 1

Reference slices =>

All slices were cut || to reference surface


Annealing: FWHM change

An03 Src 200oCSL02(111) 0.6 0.6SL05(100) 2.8 1.4SL06(211) ND 0.7

An04 Src 150oC13(1)1(1) 2.5 1.213(1)2(1) 1.3 0.513(2)1(1) 1.8 1.413(2)2(1) 1.2 0.8

Ar atmosphere Pure water

An05 Src 225oC13(1)3(1) 0.7 0.213(1)4(1) 0.65 0.213(2)2(2) 2.7 0.3513(2)3(1) 2.5 0.35

Abr.:ND - not detected13(1)… - (111) planes13(2)… - (100) planes


Effects of hydrothermal annealing during 5 days

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

0

200

400

600

800

1000

SourceSet67

13(1) 2(1)2=39.134

Hydrothermal Annealing, 150oC

An04Set55

Inte

nsity

, cn

ts

scan angle

8 9 10 11 12 13 14 15 16 17 18 19 20

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

2600

SourceSet67

13(1) 3(1)2=39.134

Hydrothermal Annealing, 225oC

An05Set67

Inte

nsity

, cn

ts

scan angle

150o C 225o C


Source slice10 at a start position

Slice12 annealed at 225o C at a start position

rotation ~-5o

-40o

Effect of TlBr crystal annealing

• Source slice10 and annealed slice12• Sample rotation in Nicole crossed

rotation -42o

rotation ~+15o


-250 -200 -150 -100 -50 0 50 100 150 200 250-40.0n

-30.0n

-20.0n

-10.0n

0.0

10.0n

20.0n

30.0n

DarkBox, troom

Emax

= 1kV/cm

SL02mp(111) SL05pm(100) SL06pm(211) SL12pm(ND)

Cur

rent

, nA

Voltage, V

<= Dark box

-250 -200 -150 -100 -50 0 50 100 150 200 250

-400.0n

-300.0n

-200.0n

-100.0n

0.0

100.0n

200.0n

300.0n

400.0n

500.0n

440 nm, troom

Emax

= 1kV/cm

*20

SL02mp 440nm SL02pm 440nm SL02mpdark

Cur

rent

, nA

Voltage, V

Irradiation: 440nm

-200 -100 0 100 200-500.0n

-400.0n

-300.0n

-200.0n

-100.0n

0.0

100.0n

200.0n

300.0n

400.0n

500.0n

SL02mp 440nm SL02pm 440nm SL02mpdark*20

440 nm, troom

Emax

= 1kV/cm

Curr

ent,

nA

Voltage, V

+ “Dark” * 20

IV-measurements


-250 -200 -150 -100 -50 0 50 100 150 200 250

-30.0n

-20.0n

-10.0n

0.0

10.0n

20.0n

30.0n

DarkBox, troom

Emax

= 1kV/cm

SL06: Source

Sl06: Ar, 200o C

Cur

rent

, nA

Voltage, V

IV: Annealing

• Annealing: Dry Ar, 200o C

-250 -200 -150 -100 -50 0 50 100 150 200 250-40.0n

-30.0n

-20.0n

-10.0n

0.0

10.0n

20.0n

30.0n

40.0n

50.0n

60.0n

70.0n

80.0n

90.0n

100.0n

110.0n

120.0n

130.0n

140.0n

DarkBox, troom

SL06: Source

Sl06: Ar, 200o C

An04D: water, 150o C

Cur

rent

, nA

Voltage, V

• Annealing: water, 150o C

(unstable characteristic)

-250 -200 -150 -100 -50 0 50 100 150 200 250

-40.0n

-20.0n

0.0

20.0n

40.0n

60.0n

80.0n

100.0n

120.0n

140.0n

160.0n

180.0n

200.0n

DarkBox, troom

SL06: Source

Sl06: Ar, 200o C


An05A: water, 225o C

Cur

rent

, nA

Voltage, V


(unstable characteristic)


Photo-Current Spectra

• Non annealed source

• Normalisation by Max200 250 300 350 400 450 500 550 600

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0SL02: Source-200 V

Rat

io o

f cu

rren

t: i

/ iM

ax

wavelengh, nm

• Annealing: Ar, 200o C

200 250 300 350 400 450 500 550 600

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0SL02: Source

SL02: Ar, 200o C

Rat

io o

f cu

rren

t: i

/ iM

ax

wavelengh, nm


200 250 300 350 400 450 500 550 600

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0SL02: Source

SL02: Ar, 200o C

An04B: water, 150o C

Rat

io o

f cu

rren

t: i

/ iM

ax

wavelengh, nm


200 250 300 350 400 450 500 550 600

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

SL02: Source

SL02: Ar, 200o C

An04B: water, 150o C

An05C: water, 225o C

Rat

io o

f cu

rren

t: i

/ iM

ax

wavelengh, nm


X-ray response

Annealing: Ar, 200o C

0 5 10 15 20 25 30 35 40 45 50-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

E=+-0.5 kV/cmbetween eletrodes

E=+-0.5 kV/cm

E=+-1 kV/cm

Cu-tube, 40 kV

SL02: Ar, 200o C

Det

ecto

r cu

rren

t, A

current, mA

Annealing: water, 150o C

Annealing: water, 225o C

0 5 10 15 20 25 30 35 40 45 50

0

2

4

6

8

10

12

14

E=~-1.5 kV/cm

E=~-1.2 kV/cm

E=+-1 kV/cm

E=~+1.5 kV/cm

E=~+1.2 kV/cm

Cu-tube, 40 kV

SL02: Ar, 200o C


An05C: water, 225o C

Det

ecto

r cu

rren

t,

A

current, mA


Conclusions

• TlBr grown from melt is stressed and the block boundaries formed have complicated character

• Annealing improves the crystal quality and as result electrical, optical and detection properties

• Annealing in pure water asymmetrically modifies these properties that is probably caused by the concentration gradient of impurities

• Several samples annealed in pure water reveal characteristics of a semiconductor doped


Acknowledgements

• Crystal growth: I.S. Lisitsky and M. Kuznetsov (GIREDMET, Russia)

• Electrode deposition Marko Vehkämäki (University of Helsinki)

• European Space Agency ESA

• Finnish Technology Agency TEKES

Department of Chemistry, University of Helsinki, Finland METOREX International Oy, Espoo, Finland...

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