Semiconductor Photon Detectors

Patras,June 2007 Gerhard Lutz, PNSensor GmbH 1

Semiconductor Photon DetectorsSemiconductor Photon DetectorsPart 1Part 1

Gerhard Lutz

PNSensor GmbH, München

for the

MPI Semiconductor Laboratory, Otto Hahn Ring 6, D 81739 München

3rd Joint ILIAS-CERN-DESY Axion-WIMPs training-workshop

Patras, GreeceJune 19-25, 2007


IntroductionIntroduction

Development of position sensitive silicon detectors initiated by developments in particle physics attracted interest of X-ray astronomers at MPE

MPE activities in X-ray astronomy based on X-ray mirror imagingFocal gas proportional detector (ROSAT) replaced withsilicon detector (pn-CCD) in XMM/Newton

Development of these detectors required new technology not available in industry

Semiconductor Laboratory founded 1992 by two Max-Planck institutesAim: Development of novel detectors for institute experiments in particle physics and astrophysicsComplete high-tech production lineDevelopments based on new (own) detector concepts

Attention initially concentrated on X-rays, now expanded to include optical region and may extend further to near infrared

Talk will describeo Principles and properties of semiconductor detectorso Capabilities of the laboratory

o Institute projects requiring photon detectorso Further developments

•


ContentContent

• Basic Semiconductor Properties and Structures (diode, drift detector)• Photon detection in semiconductor detectors

• PN-CCDs for X-ray astronomy (XMM/Newton, e-Rosita)• DEPFET

Function PrincipleProperties

• DEPFET detectors for X-ray spectroscopic imagingPixel detectors for XEUSMacro-pixel detectors for SIMBOL-X and BEPI-COLOMBO

• RNDR (Repetitive Non Destructive Readout) detectors with sub-electron noise• DEPFET Ping-Pong structure• CCDs with RNDR readout

• Avalanche Detectors• Avalanche drift diode• CCDs with avalanche readout

• Low background photon detectors


Why semiconductor detectorsWhy semiconductor detectors

• Excellent properties for measuring ionization:small band gap (Si 1.12eV) ⇒ low e-h pair generation energy (Si 3.6 eV) (ionisation energy for gases ≈ 30 eV) ⇒precise energy measurementprecise energy measurementHigh density (Si 2.33 g/cm2) ⇒ large energy loss/length for ionising particles ⇒ thin detectors; small range δ-electrons;precise position measurementprecise position measurementAlmost free movement of electrons and holesMechanical rigidity; self supporting structureDoping creates fixed space charges; building of sophisticated field structuresintegration of detector and electronics in single detector and electronics in single devicdevicee


Basic Detector: Semiconductor DiodeBasic Detector: Semiconductor Diode

• Most basic: reversely based diodeElectron-hole pairs generated by ionizing radiation (photons or charged particles) are separated by electric field and collected at electrodesTypical structure:p+ n- n+


(Diode) Strip Detectors(Diode) Strip Detectors

• Divide diode into strips and measure charge arriving at individual strips ⇒ position measurement• Further developments:

charge division readoutdouble sided readoutcapacitive coupled readoutbiasing methodsbreakdown protectionradiation hardening


A simple processing sequence: strip detectorA simple processing sequence: strip detector


TheThe MPI MPI SemiconductorSemiconductor LaboratoryLaboratory

Capabilities:•Everything from wafer to tested detector•Design and Simulation•Complete detector technology•Sophisticated test and analysis equipment and tools

Separation, mounting, bonding

Quality assurance and control

System test equipment

photo resist deposition

photo lithography

visual inspection

wet chemistry

sputter

oxidation


• Why own technology:Use of ultra-pure silicon: properties not to deteriorate during processingwafer size defect free processingdouble sided processingsophisticated detectors require complete and detailed control over process


(Historical)(Historical) Detectors for particle physicsDetectors for particle physics

• Particle tracking: position measurementFirst strip detectors (NA11/NA32)

First double sided Capacitive coupled, simple biasingRadiation hardPixel sensors(First drift detectors)Readout electronics

Na11 strip detector: charmed particles

Aleph strip detectors: e+e- collider

HERAB or ATLAS?


Semiconductor Drift ChamberSemiconductor Drift Chamber• Sideward depletion

Diodes on both surfacesPotential maximum in middle plane

• Drift chamber(Gatti and Rehak 1984)Sideward depletion + graded potential on outer surfacesignal charge collected in centre valley, moves parallel to surface towards collecting anodePosition (from drift time) and/or energy measurement (from signal charge)small capacitive load gives good energy resolution

• Basis for spectroscopic imaging detectors to be described


Noise in semiconductor detectorsNoise in semiconductor detectors

• Noise created in electronics:• - Serial noise with 2 components

Thermal (white) noiseLow frequency (1/f) noise

• represented by noise voltage at amplifier input

• Noise created in detector- Parallel noise

represented by noise current source parallel to the detector

•

Charge sensitive amplifierCharge sensitive amplifier


DetectorsDetectors notnot coveredcovered in in presentationpresentation

• Strip detectors and standard drift detectors used for charge particle tracking• Drift diode used for X-ray spectroscopy

• Drift detector principle is basis for several spectroscopic imaging detectors to be described:PN-CCDsDEPFETs


PN-CCDs


PNPN--CCD (CCCD (Chargeharge CCoupledoupled DDeviceevice) principle) principle

•Pn-CCD:Based on drift chamber principleCharge transfer in bulk (~10µm depth)Spectroscopic imaging


pnpn--CCDCCD forfor ESAESA‘‘ss XMMXMM--NewtonNewton satellitesatellite

Detectors for X-ray astronomy

• XMM: three X-ray telescopes• one dedicated to imaging (with pn-CCD) • two with additional reflecting gratings

(andMOS CCDs) • one optical telescope• all pointing on same object

• Wolter I type mirror telescopes• 58 nested mirror shells • Wall thickness 0.5 to 1mm Ni


MOS-CCD (´video CCD´)

• MOS transfer gates

• buried channel

• partial depletion

• frontside illumination

• serial readout

MOS-CCD (´video CCD´)

• MOS transfer gatesimplanted pn-junctions

• buried channel

deep transfer

• partial depletion

full depletion

• frontside illumination

back entrance window

• serial readout

1 preamp / channel

pn-CCD

pnpn--CCDCCD principleprinciple


Simulation of Simulation of pnpn--CCDCCD chargecharge transfertransfer

Device simulation

Charge transfer in pn-CCD


pnpn--CCDCCD performanceperformance

• largest monolithic CCD

6 x 6 cm²

384 x 400 pixel

150 µm pixel

• fast, parallel readout

5 msec full frame

• low noise

4 el. rms

• high quantum efficiency

90 %

• radiation hard

400 Mp/cm²


Wafer size detectorWafer size detector

• XMM 6x6 cm2 CCDswere produced on 4 inch wafer

• CAST uses one segment prototype of 1x3cm2

4 inch wafer(Ø = 100 mm)(d = 280 µm)


New 6 inch technologyNew 6 inch technology

• Frame store pn-CCDs for e-ROSITA produced in6 inch technology

wafer size:6 inch,Ø = 150 mmd = 450 µm


High High speedspeed frameframe storestore pnCCDs pnCCDs forfor XX--raysraysthethe eROSITA eROSITA conceptconcept

FS pn-CCD for the eROSITA mission (MPE, IAAT, ROSKOSMOS)

• format 384 x 384 x 2, geom.: 19.25 cm2 per chip, • pixel size 75 µm □ image, 48 µm □ in frame store• eROSITA sensitive chip area: 2.9 x 2.9 cm2 = 8.4 cm2 (7 x)• eROSITA has 1.03 Mega Pixel on 60 cm2


eROSITA typepnCCDs:384x384x275x75 µm2

This picture:256x256x2 pixel75x75 µm2


image area384 x 384 Pixel

75μm x 75μm

frame store area384 x 384 Pixel

75μm x 51μm

37 mm

5

6 m

m

X-rayexposure

fast transfer of image

readout of image (shielded against X-rays)

28.8 mm

2

8.8

mm

CAMEX128 channels

CAMEX128 channels

ADC

CAMEX128 channels

ADC ADC

25 x 39 mm

Chip size:35 x 55 mm2,i.e. 19.25 cm2


Energy Energy resolutionresolution @ C_K of a pnCCD@ C_K of a pnCCD

110 eV

277 eV

525 eV

Trigger Threshold: 22 eV

50 eV


5151µµm pnCCD m pnCCD withwith a a doubledouble--sidedsided readoutreadout,,mountedmounted ontoonto a a ceramicceramic substratesubstrate

detector size = 27×13.5 mm2

51 µm pixel size528×264 pixel in total,264×264 in each image & storage

areareadout transfer to both sidesimage transfer time = 20 µsOOT probability = 2% @ 1000 fpscharge transfer loss CTI ≈ 10-6

i.e. total charge loss < 0.05 %charge handling capability > 106 e-

100% fill factorreadout noise vs. frame rate:

1.8 e- @ 10 .. 400 fps2.3 e- @ 400 .. 1.100 fps

With binning: 2.3 e- @ 2.200 .. 4.400 fps

All measurements were performed@ - 40 o C

this pnCCD system is used in:adaptive optics, high time resolution astrophysics,synchrotron radiation, transmission electron microscopy, channeling radiation, X-ray microscopy, etc . . & CFEL


Low Low energyenergy responseresponse of of pnCCDpnCCD

• Measured at FLASH (DESY)

E = 90 eV ± 0.1 eV# e-h pairs: 25 ± 1.6ENC: 2.3 el. (rms)

pile up events

Triggerthreshold@ 25 eV(4 σ cut,i.e. 2 e-)

Semiconductor Photon Detectors

Documents

Transcript of Semiconductor Photon Detectors