Camera CCD in sviluppo all’XUVLab per un esperimento su razzo, precursore dell’esperimento UVC del Solar Orbiter

Compact (72mm x 72mm x 50mm)

Lightweight Fully vacuum compatible 4096 x 4096 maximum

CCD format Three-stage Peltier cooler Two available thermal

links between the CCD and the TEC (ΔT=-85°C/-60°C)

Very low noise preamplifier stage (1.8 nV/Hz r.m.s.)

Forme d’onda del CCD (fasi orizzontali in alto e verticali in basso) come appaiono ad uno strumento chiamato “analizzatore di stati logici”

Problemi dei rivelatori UV

low UV sensitivity, unstable,

not radiation hard, highly visible sensitive

PhotomultipliersPhotomultipliers

CCDCCD

Photodiodes

(a-Si, treated Si, Al)

Photodiodes

(a-Si, treated Si, Al)

Micro-Channel PlatesMicro-Channel Plates high voltage, hygroscopic photocathodes, unstable gain, operated in UHV

low UV sensitivity, unstable,

not radiation hard, highly visible sensitive

high voltage, 110 nm,

low fluxes, dark current

Ideal UV detector for space

visible blindnessvery low noise

high sensitivity to XUV photonschemical stability

radiation hardness

Requests

Specifiche per i rivelatori del Solar Orbiter

• Solar blindness < 10-7

• Operating temperature ± 50°C• Frame rate 1000 s -1

• Frame format 2K 2K • Pixel size < 20 m• Radiation hardness 50 Krad• Weight 1 kg

Common specification requirements for the imaging and spectroscopic instruments for remote sensing are

Photon fluxes (counts/s/px)

Imaging 103

Spectroscopy 102-103

3-D spectroscopy 105

Photon fluxes (counts/s/px)

Imaging 103

Spectroscopy 102-103

3-D spectroscopy 105

Rivelatori UV disponibiliPhoton Counting

MCP + XDL

MCP + APS

MCP + CID

Advantages Photon counting Solar blindness Radiation hardness Spatialised Operating @ Tamb

Disadvantages Efficiency < 30% High voltage biases Weight Spatial resolution (centroid

required) External electronics (to be

shielded!)

Charge integration

None!

CCD is not rad-hard

Alternativa: nuovi materiali fotosensibili

Eg = 5.5 eV dark current < 1 pA

visible rejection (ratio 10-

7)

high EUV sensitivity Highly radiation hard Chemical inertness Mechanically robust (high Young modulus) High electric charge mobility = fast response time Low dielectric constant = low capacitance

Diamond & nitrides are appealing materials for the EUV photon detection. Their main properties are hereafter sumarized :

Rivelatori a diamanteDevice area: 6 6 mm2 Thickness: 40 µm Grain size: 20 µmSensitive area 4 mm2

Interdigitated contacts

spacing 20 mthickness 0.1 melectrode width 15 m No thermal annealing

back contact 25 mm2

Dark current

-200 -150 -100 -50 0 50 100 150 200-1.4

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Au

Voltage (V)

Cur

rent

(pA

)

Stabilità e risposta temporale

-200 0 200 400 600 800 1000120014001600

0

20

40

60

80 36 KV/cm

28 KV/cm

20 KV/cm

Pho

tocu

rren

t (nA

)

Time (s)

0 20 40 60 80 100 120 140 160 180 200

0,0

0,2

0,4

0,6

0,8

1,0

1,2

20 KV/cm 28 KV/cm 36 KV/cm

Nor

mal

ized

Pho

tocu

rren

t

Time (s)

Toff = 30 %

Quantum Efficiency

200 400 600 800 10001E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0,01

0,1

1

10

100

E = 28 KV/cm

Ele

ctro

n / p

hoto

n

Wavelength (nm)

100 120 140 160 180 200 220 240 2600,01

0,1

1

10

100

1000

10000

QE Diamond QE CCD QE MCP + KBr

Qua

ntum

Effi

cien

cy (%

)Wavelength (nm)

[1] Naletto, Pace et al, 1994

[2] Wilhelm et al.,1995

[2]

[1]

Diamond efficiency Comparison with other detectors

E. Pace et al., Diam. Rel. Mater. 9 (2000) 987-993.

Diamond – Responsivity

-200 -150 -100 -50 0 50 100 150 200-1,2

-1,0

-0,8

-0,6

-0,4

-0,2

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

Voltage (V)

Cur

rent

(pA

)

Dark current @ room temperature

Vbias = 30 V

Our proposal: flip-chip CMOS imager

Select the most appropriate sensitive material

Exploit the advantages offered by the CMOS technology to fabricate system-on-a-chip detectors

Join the best material and on-chip CMOS electronics by means of the consolidated flip-chip technology (applied to IR photon and particle detection)

The idea

Diamond bump-bonded detector

Incident radiation

Open electrode

CMOS imager

Sensitive layer

Pixel array

12.5 m

Applicazioni attuali Applicazioni attuali

alla fisica delle particellealla fisica delle particelle

Advantages of flip-chip technology

High responsivity Visible rejection Available technologies Frame format and pixel size in the spec On-chip read-out electronics Radiation hardness Compact detector (reduced weight) Low power consumption High frame rate Windowing

EUV sensitive layers bump-bonded on CMOS imagers could have many appealing features, such as: