photodetectors - ndipndip.in2p3.fr/beaune05/cdrom/sessions/mangeot.pdf · 4 applications of...

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PhotodetectorsPhotodetectors

Philippe Mangeot CEA/DSM/DAPNIA

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IntroductionIntroductionScope of the tutorialScope of the tutorial

Light detection of photons from UV to IRLight Pulses measurementsImagingBasics in physics principles, technology and applications

Out of scope Out of scope (my choice !)(my choice !)Film or phosphor image plateSolar photovoltaic silicon cellsDirect X ray or far UV detection and imagingBolometer or far IR detectionExotic and/or lab devices (quantum dots or wells, heterostructure, multibandgap…)

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SourcesSourcesMost important sources were borrowed from the web pages of :

• Hamamatsu : http://sales.hamamatsu.com/en/home.php• Photonis : http://www.photonis.com/• Electron Tubes Limited : http://www.electrontubes.com/• e2v Technologies : http://e2vtechnologies.com/ (formerly EEV)• Delft Electronics Products: http://www.dep.nl/•SensL : http://www.sensl.com/•Micron : http://www.micron.com/•and many others

from the web pages of Amos Breskinhttp://www.weizmann.ac.il/home/detlab/

And from many other lectures and presentations, in particular by:Katsushi Arisaka (UCLA)Thomas Patzak (IN2P3 / APC)Jerry Blazey (Northern Illinois University)

Thank you and many apologizes (overall for the ones I forgot to cite!)

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Applications of Applications of photodetectorsphotodetectorsEverywhere !Everywhere !

Look around you, they are everywhere, you donLook around you, they are everywhere, you don’’t even know or notice !t even know or notice !Media (digital camera, camcorder, cell phones, CD reader…)Telecom (optical fiber links, optical couplers…)Laser applications (measurement, gas analysis, barcode readers…)Medicine (gamma and PET camera, digital X rays, endoscopies…)Biology ( DNA sequencing, Immuno-assay, biochip…)Industry (chemical and surface analysis, process control, shape analysis…)Defense (night vision, earth observation…)Mining (oil well logging, rock analysis…)Physics (a rather small part of the market !)

• Solid state, synchrotron radiation, plasma science• Particle and nuclear physics • astronomy and astrophysics

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Types of Types of photodetectorsphotodetectors

Vacuum devicesVacuum devicesPhotomultiplierMultichannel platesHybrid photon detectors

Solid state devicesSolid state devicesPhotodiodes, phototransistors and PIN diodesAvalanche photodiodesSilicon photo multipliersImaging arrays photo sensor

• Charge coupled devices• CMOS Active Pixel Sensor• a:SiH Thin Film Transistor array

Gaseous Gaseous photodetectorsphotodetectorsDrift and MWPC

• Gas photocathode• Solid photocathode

Micropattern gas chamber

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Some photometric unitsSome photometric unitsCandela

•• Luminous intensityLuminous intensity of a source E=1,464.10-3 watt/stéradian @ 555nm • Amount of light produced by 1/60 cm² of a black body @ 2046 K

Lumen•• luminous fluxluminous flux through a solid angle of 1 steradian by a source of 1Cd

Lux• unit of illuminationillumination : 1 lumen per square meter

Direct sunlight 100,000 - 130,000 lux

Full daylight, indirect sunlight 10,000 - 20,000 lux

Overcast day 1,000 lux

Indoor office 200 - 400 lux

Very dark day 100 lux

Twilight 10 lux

Deep twilight 1 lux

Full moon 0.1 lux

Quarter moon 0.01 lux

Moonless clear night sky 0.001 lux

Moonless overcast night sky 0.0001 lux

1 Watt = 683 lumen @ 555 nm1 Watt = 683 lumen @ 555 nm

Photo detector sensitivityOften given in A/lm

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Vacuum Devices : PMTVacuum Devices : PMT

PrinciplePrinciple

photon

photoelectronSecondaryelectrons

photocathode

Glass window

dynodesecondary emission δi ≅ 2 - 10

anode Lastdynode

SocketHV dividerpreamp

Glass tubeVacuum = 10-4 P

focusingelectrode

Gain : G = δ1⋅δ2⋅δ3 ⋅⋅⋅ δnCharge : E=Nγ⋅QE⋅CE⋅G

QE =Quantum efficiencyCE= collection efficiency

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Main parameters and performancesMain parameters and performancesQuantum Efficiency (QE) 20 to 30% @ 400 nmPhotoelectron Collection Efficiency (CE) 70 to 90%Gain (G) up to 107

Excess Noise Factor (ENF) ~ 1.3 (see later)

Energy Resolution (σ/E)

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Photocathode Quantum Efficiency (QE)Comparison to emission spectra of common Comparison to emission spectra of common scintillatorscintillator materialsmaterials

Bialkali:• Sb-Rb-Cs• Sb-K-Cs

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Vacuum Devices : PMTVacuum Devices : PMTPhotocathode Quantum Efficiency (QE)

Various photocathode materialsVarious photocathode materials

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Transmittance of glass windows

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Secondary emission

Gain

δ = a . Vk

a : constant k = 0.7 to 0.8

G = CE. δ1. δ2. δ2. …δi….. δn

where δi = secondary émission coeff of ith dynode

nknknnk VAnVaEaG ⋅⋅ ⋅=+

⋅=⋅= )1

()(

Assuming uniform voltage drop between dynodes

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Gain and dark current

ThermalPhotoelectronEmission

LeakageCurrent

FieldEffect

This and the 2 next slides from a lecture of Katsushi Katsushi ArisakaArisaka (UCLA)

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Energy resolution, Excess Noise Factor• Ideal case

• Real case : electronic noise (ENC) and amplification statistics (ENF)

• Excess Noise Factor

2

2

Input

OutputENFσσ

≡

γγ

γσNN

NE

1==

2

⎟⎟⎠

⎞⎜⎜⎝

⎛

⋅⋅⋅+

⋅⋅=

PGCEQENENC

CEQENENF

E γγ

σ

Increase of the variance of energy distribution due to amplification statistics

n

ENFδδδδδδ ⋅⋅⋅⋅

+⋅⋅⋅+⋅

++=21211

1111For a PMT with n dynodes

The first dynode secondary emission The first dynode secondary emission coeffcoeff dominatesdominates

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Single photon detection

ENF is related to Peak to Valley RatioIf δ1 >>5 => ENF<1.4

Clear single PE can be seen.

111121211_

−=⋅⋅⋅⋅

+⋅⋅⋅+⋅

+=⎟⎠⎞

⎜⎝⎛ ENFE nPESingle δδδδδδσ

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Dynode geometryDynode geometry

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Vacuum Devices : PMTVacuum Devices : PMTTiming propertiesTiming properties

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Basic peamplifier scheme

Voltage divider bias circuit

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They come in many different shapes, size (up to 20” !) and performances.One of the most important market is medical imaging 300000 PMT’s year.(2000 gammas camera/year, 80 PMT’s200 PET cameras 800 PMT’s)

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Applications and marketApplications and marketMedical imagingIndustry (oil and mining)Physics

Excerpt from HAMAMATSU applications guide from their web site

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Vacuum Devices : MCPVacuum Devices : MCP

Multi Channel PlateMulti Channel PlateStructure and principle

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Structure and principlephoton photoelectronphotocathode

∆V ~ 300 V

∆V ~ 3000 V

∆V ~ 300 V

Glass window

dual MCPGain ~ 106

Anode may be pixilated

Chevron structure :•reduces space charge•reduces ion feedback•Increases gain

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Vacuum Devices : MCPVacuum Devices : MCPTechnology

• Monofiber draw• Multifiber stack and draw• Billet stacking• Slicing (θ~ 5 to 10°)• Etching of core glass• Reduction of lead glass

– H2 @ 250 to 450°C– =>Semiconductive layer

• Vacuum deposition– NiCr electrodes

Core : hard etchable glassCladding : lead glass

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Main parameters and performancesMain parameters and performancesGain

• single stage : G ~ 103 to 104

• Dual MCP : G ~ 106 to 107

• Low transient time ~1 ns• Transient time spread ~100 ps• Sub-ns rise and fall time

Function of :α = Ratio Length/diameterδ =secondary emission coeffG =exp ( K . G =exp ( K . αα))

K = f(HV, α) gain factor

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Applications• Light or image intensifier, night and IR vision

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Applicationsimage intensifier

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Vacuum Devices : HPDVacuum Devices : HPD

Hybrid Photon DetectorHybrid Photon DetectorBasic

• Photon conversion • Electrostatic acceleration

– 10 to 30 kV

• Ionization in Si detector– 3.6 eV for e-h pair– PD : Q ≤ HV / 3.6– APD additional gain ~ 50

• Imaging capability– Electrostatic optics or

proximity focussing– Pixelized detector– R/O ASIC aboard

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Hybrid Photon DetectorHybrid Photon DetectorTechnology

5” HPDBialkali KCsSb UV extendSi 2048 ch 1x1mm²HV = 20 kVC.Joram Beaune 2002

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Main parameters and performances

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Vacuum DevicesVacuum Devices

Other devices : multi stage phototubesOther devices : multi stage phototubes

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Typical Values and Resolution Typical Values and Resolution of Various Photon Detectors of Various Photon Detectors

QEQE CColol δδii ENFENF GG ENCENC σσ/E/E

IdealIdeal 1.01.0 1.01.0 10001000

1010

--

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10001000

10001000

1.01.0 101066 00 √√1/N1/N

PMTPMT 0.30.3 0.90.9 1.31.3 101066 101033 √√4/N4/N

PDPD 0.80.8 1.01.0 1.01.0 11 101033 √√1.4/N+(1000/N)1.4/N+(1000/N)22

APDAPD 0.80.8 1.01.0 2.02.0 100100 101033 √√3/N+(14/N)3/N+(14/N)22

HPDHPD 0.30.3 0.950.95 1.01.0 101033 101033 √√3/N+(3/N)3/N+(3/N)22

HAPDHAPD 0.30.3 0.950.95 1.01.0 101055 101033 √√3/N3/N

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⎟⎟⎠

⎞⎜⎜⎝

⎛

⋅⋅⋅+

⋅⋅=

PGCEQENENC

CEQENENF

E γγ

σ

From a lecture of Katsushi Katsushi ArisakaArisaka (UCLA)

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Solid state Solid state photodetectorsphotodetectors : PD: PD

Photodiodes, phototransistorPhotodiodes, phototransistorBasic

• Bulk Si =>N layer• P layer on top (boron doped)• Depleted zone between P and N• If Eλ > Eg (1.12 eV for Si)→e- jump to conduction band→h+ left in valence band→e- (h+) drift to N (P) layer→current

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Reverse bias• Photo conductive mode (instead of photovoltaic)• Increase depletion zone thickness• Reduce junction capacitance • Increase speed

Phototransistor• Very commonly used device

PIN diode• Add an intrinsic layer• Between P N layers• Same results as reverse bias

– + reduction dark noise– Increase speed– Higher absorption coeff

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Solid state : APDSolid state : APD

Avalanche Avalanche PhotoDiodePhotoDiodeBasic

• Photons create e- h+ pairs in intrinsic zone

• Electrons drift to depleted zone• Multiplication by ionizing

collisions

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Active Area 5x5 mm2

Operating Voltage @ M=50 ~380 V

Capacitance @ M=50 80 pF

Serial Resistance 3 Ω

Dark Current @ M=50 < 10 nA

Excess Noise Factor @ M=50 ~2

Quantum Efficiency @ 470 nm 80 %

dM/dV x 1/M @ M=50 3.0 %/V

dM/dT x 1/M @ M=50 -2.4 %/K

Summary of APD parameters

Applications Applications Main application : optical link Physics :

• CMS e-cal

APD`s designed for the CMS ECALBy Hamamatsu Photonics

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CMS eCMS e--cal cal APDAPD’’ss

0.1

1

10

100

1000

10000

0 50 100 150 200 250 300 350 400 450

Voltage [V]

Gai

n

0

10

20

30

40

50

60

70

80

90

100

300 400 500 600 700 800 900 1000Wavelength [nm]

Qua

ntum

Effi

cien

cy [%

]

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Solid state : Solid state : SiPMSiPM

Silicon Photomultiplier Silicon Photomultiplier Small depleted layer (0.5 µm) very high field =>Geiger avalancheSimilar : MRS (Metal-Resistor-Semiconductor)

array of small Geiger APDs onto the same substrate (less then 1 photon per cell)Geiger discharge quenched by passive resistor (400kΩ) on each pixel

P. Buzhan et alMEPhI & PULSAR in Moskow

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Main properties

SiPM pulse height distributionLED illumination

Gain versus bias voltageG = Cpix.(Vbias – Vbreak)/eslope gives pixel capacity (C = 41fF)

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Some problems

Quantum efficiency :• Low for a Si device• low fill factor• thickness of front layer

Dark noise vs bias voltageDecrease to 10 kHz at -50°C @ G= 106

P. Buzhan et al. NIM A 504 (2003) 48-52

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Solid state : VLPCSolid state : VLPC

Visible Light Photon Visible Light Photon CounterCounter

Formerly “Solid State Photo Multiplier” by RockwellPrinciple of Operation

• Impact ionization of As doped impurities in Si (En ~ 54meV)

• Impurity band conduction (conduction hopping at low temp.)

• Single carrier photomultiplication

•+ •-

IntrinsicRegion

GainRegion

DriftRegion

SpacerRegion

Photon

•h

Substrate

•e

D+ flow

E field

Undoped Silicon

(Blocking) Layer

Doped Silicon Layer

Heavy As doping

Gain Region

Drift Region

Top Contact (+)

Bottom Contact (-)

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Solid state : VLPCSolid state : VLPC

Scifi tracker of DØ8 pixels VLPC chip

Advantages• Quantum Efficiency ~ 90%• Avalanche gain ~ 30,000• Pulse duration ~ 1nsec

Disadvantages• High dark counts ~ 20,000/s• Highly sensitive to room temp.

IR photons•• 6 to 9 K operation temp6 to 9 K operation temp

Low light level LED calibration

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Solid state Arrays: CCDSolid state Arrays: CCD

Charge Coupled DeviceCharge Coupled DevicePrinciple

• Array of small Photodiodes• Light integration• Transfer thru the matrix

Transfer from well to well (pixel)2 phases clocked gates Detail of a pixel and

operation principle

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Readout architectureReadout architecture

interline transferFast frame transfer

Full frame transferSmearing : needs a shutter but simpler chip

Frame transferLong exposures

Typical R/O speed = 5 MHz⇒FFT at 5 frames /s for a1024x1024 pixel CCD

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Main parametersMain parametersQuantum efficiency

• Front illumination : QE ~ 50% range λ = 400 to 800 nm• Back illumination : QE 80% range λ = 200 to 1000 nm

Dark signal at 293 K ~ 1000 to 10000 e-/pixel/s

Quantum efficiency of CCDBack vs front illumination

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ApplicationsApplicationsConsumer media equipment Scientific : spectrometry, biomedical imaging…Astronomy

The focal plane of MEGACAMTelescope CFH (Hawaii)• 40 CCD’s• e2v Technologies model CCD42-90• 2048x4612 pixels (13.5 x 13.5 µm²)• Back illuminated (λ 350 to 1000 nm)• Cooling at - 120°C• 400 Mpixel, 30s readout • 80 Go of data / night

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Solid state Arrays: APSSolid state Arrays: APS

Active Pixel Sensor : CMOS imager Active Pixel Sensor : CMOS imager Matrix of pixels = photodiodes + preamp and gatesrandom addressing R/O Classical CMOS processing

PhotodiodeActive-Pixel Architecture

PhotogateActive-Pixel Architecture

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Main parameters and Main parameters and performancesperformances

Sensitivity : 1 to 2 V/lux-secDark noise : 10 mV/s @ 60°CDynamic : 40 to 60dB (depends from ADC on chip)Speed : up to 200 frames/s in VGA format (640x480 pix)Size : up to ½” 4000 x 4000 pix (3 x 3 µm²)Low cost, standard IC processing, high yieldBut :Low efficiency : poor fill factor (microlenses improve)

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ApplicationsApplicationsCamera “on chip”Low cost still camera, web cam, process and shape control

Quality and performances steadily improveQuality and performances steadily improveMedical applications : dental X ray , endoscopy

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Solid state Arrays: above ICSolid state Arrays: above IC

Above IC : Smart Pixel and TFAAbove IC : Smart Pixel and TFASeparate photon conversion and R/O electronicSeparate photon conversion and R/O electronic

“smart pixel”• Photodiode array bonded on top of R/O chip

Thin Film on ASIC• a-Si:H evaporated on top of R/O ASIC

Other development at CERNPierre Jaron

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Solid state Arrays: TFTSolid state Arrays: TFT

Imaging plate : aImaging plate : a--Si:HSi:HThin Film TransistorThin Film Transistor

Same design and process than LCD flat screens

• Matrix of amorphous Silicon transistors evaporated on top of glass panel , plastic film or Siwafer

• H and V random addressing readout

May be coupled to scintillator

• Gd2O2S:Tb phosphor screens or CsI(TI) scintillating layers

• Digital X ray plate => columnar grown polycrystalline CsI

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Solid state Arrays: TFTSolid state Arrays: TFT

Main performancesMain performancesSize : up to 400 x 400 mm², 3000 x 3000 pixelsFill factor : 30 to 70%Readout time : up to 30 frame/sDynamic : 14 bit

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Gaseous photo detectorsGaseous photo detectors

Gaseous photocathodeGaseous photocathodeTEA, TMAEMultistage chamberdrift chamber (DELPHI,SLD)

Solid photocathodeSolid photocathodeCsI and other stuffWire or pad chamber, asymmetric drift chamberMicro pattern gas chamber

• Micromegas• GEM• Gaseous phototubes

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E.Nappi INFN Bari Beaune 2002

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Gaseous photocathodeGaseous photocathodeTEA, TMAE

• Photon conversion directly on gas molecule• Eλ must be > Ionization potential of gas • Most gas have Eion > 10 eV => λ = 1240/10 = 124 nm far UV• But

– TEA triethylamine [(C2H5)3N] EEionion=7.5 eV=7.5 eV– TMAE tetrakis(dimethylamino)ethylene. [C10H24N4 ] EEionion=6.1eV=6.1eV

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Multistage chamber• First RICH in operation• E605 at FNAL• 15 m He radiator• 2 chambers• 40 x 80 cm²• Ar +TEA• 3% TEA (bubbling @ 10°C)• Gain 4.106 to 107

Advantages of TEA• High vapor pressure• Good QE• Small free mean path for UV

disadvantages of TEA• Too high threshold 7.5 eV (165 nm)• Need UV optic (mirror,windows)• Needs very high transmission Cerenkov medium

MgF window

Conversion gapPreamp gap

Drift gap

MWPC0 V-2000 V

-3000 V-6000 V-6500 V

-2000 V

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drift chamber (DELPHI,SLD, OMEGA)• TMAE

– Use of quartz windows– High QE

• Thick detector– Improve absorption

• Drift zone– Eliminate parallaxe

• End detector– X , Z detection– Time => Z coordinate

• Drawback of TMAE– Low vapor pressure– Long absorption range– Could need to warm up– Aggressive stuff

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Solid photocathodeSolid photocathodeCsI first choice

• Quartz windows• Good QE• Gas resistant

– If no H2O or polluants

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Micro pattern gas detectorMicro pattern gas detectorMicromegas

3 mm

100 µm

-800 V

-500 V

0 V

Drift space

Amplification space

Photon transmissionPhoton reflection

CsI photocathode may be deposited under the drift electrode (transmission mode) or on top of the micromesh (reflection)High gain reachable:•Low ion/photon feedback•Optical screening

Single photon amplitude spectrum CsI photo cathodeY.GiomatarisNucl.Instrum.Meth.A449:314-321,2000

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Micro pattern gas detectorMicro pattern gas detectorGEM

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Gaseous photomultiplierGaseous photomultiplierPossible extension of QE to visible lightBialkali photocathode in sealed detectorUltra pure CH4 or Ar/CH4

Multi GEM provides• High gain• No ion/photon feedback• Good single PE detection

Very exciting perspectiveVery exciting perspective

Amos Amos BreskinBreskin et al et al WeizmannWeizmann Institute of ScienceInstitute of Science

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TheThe EndEnd

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MCP pores microphotography

photodetectors - ndipndip.in2p3.fr/beaune05/cdrom/sessions/mangeot.pdf · 4 applications of...

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