P17-Semiconductor Photon Detectors

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 1/28

17. Semiconductor Photon Detectors

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 2/28

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 3/28

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 4/28

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 5/28

The Internal Photoeffect: Photoconductivity

Æ Excited carriers remain within the material, serve to increase electr ical conductivi ty.

.

Transport: An applied electric field induces these carriers to move,which results in a circuit current.

Amplification: large electric fields enhance the responsivity of the detector.

Photoconductors

Quantum efficiency Photon noisePhotoelectron noise 

Avalanche photodiodes (APD) Response time.Gain noise

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 6/28

Quantum efficiency of photodetectors

Internal Quantum Efficiency

α η  −

⎣ ⎦= = −int

 1

Number of Photons *Entering* detector de

( ) α ζ ν 

η  −⎡ ⎤⎣ ⎦= = − − =ext

/Number of Collected electrons

Number of Photons *Incident* on detector 1 1

/F

ph

o

di q

PR e

h

Fresnel loss Fraction absorbed

in detection region

ur ace recom na on e ec

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 7/28

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 8/28

Photoconductors

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 9/28

Photoconductors

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 10/28

Photodiodes

n

P +- i p

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 11/28

Two operation modes of PN photodiodes

-

operation of PDs

or -c rcu p o ocon uc ve

operation of PDs

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 12/28

Open-circuit (photovotaic) operation of PDs

Photovoltage Vp

with increasing photon flux.

This mode of operation is used,

for example, in solar cells

Short-circuit operation of PDs

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 13/28

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 14/28

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 15/28

Heterojunction Photodiodes

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 16/28

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 17/28

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 18/28

Comparison CCD/CMOS sensorsCMOS: low cost CCD : medium to high-end

Source: B. Diericks: CMOS image sensor concepts. Photonics West 2000 Short course (Web)

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 19/28

Charge-coupled devices (CCD)

charge transfer to next pixel cell

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 20/28

 • Vertical charge transfer 

•

• Output capacitor reset

CCD

Outputcapacitor 

Amp

or zon a eg s er  

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 21/28

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 22/28

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 23/28

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 24/28

■

Very tolerant to high-energy radiation sources (long life time).■ On- chip system integration

(low power, low weight and compact designs).

■ g spee ow no se opera on

(inherently a parallel- random access readout device).

Deficiencies

■

Currently lacks performance in most areas compared to the CCDc arge genera on co ec on rans er an measuremen .

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 25/28

Avalanche Photodiodes (APD)

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 26/28

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 27/28

APD with only one type of carrier (e or h) is desirable.

: ionization coefficients of e and h

Ionization ratio :

Æ Æ Æe Æ h Æ e Æ …..

-

7/27/2019 P17-Semiconductor Photon Detectors

http://slidepdf.com/reader/full/p17-semiconductor-photon-detectors 28/28

APD gain