The mechanisms of photo-conversion in SiPM Elena Popova Moscow Engineering and Physics Institute Corsica meeting on fast timing April 29-30, 2013

Corsica timing April 2013 E.Popova MEPhI R 50  h pixel U  60V substrate Each pixel – reverse biased above breakdown p-n-junction operated in selfquenching Geiger mode Silicon Photomultiplier (SiPM) Multipixel device with common readout Lets consider the way for SiPM signal

Corsica timing April 2013 E.Popova MEPhI The way of signal. 1D R E n + - p U bias 1.Photoeffect (light absorption) - 0 time 2.Diffusion inside undepleted region (  0 fields) -  =L 2 /D D=38cm 2 /c L=1  m  250ps 3.Drift in depleted region (low fields) 10 7 cm/c – saturated e - velocity x=3  m t  30ps 4.Avalanche build up (high fields) – several times*(3) T  100ps 1  3  m 1m1m

Corsica timing April 2013 E.Popova MEPhI 1D simulation by using ISE TCAD. Diffusion from entrance window. Laser pulse 10ps 400 nm (x 0 =100nm) Fixed intensity Reverse biased pn-junction Time, ps Current, A Doping distribution and build-in fields are not constant Should be weak sensitivity to applied voltages (depletion region should not changes much) 1) ) ) ) depth d,  m Delay, ps FWHM, ps Jitter component

Corsica timing April 2013 E.Popova MEPhI Diffusion from substrate Should be weak sensitivity to applied voltages (depletion region should not changes much)

Corsica timing April 2013 E.Popova MEPhI Avalanche build up 1D Impact ionization in high electric fields  electron  hole Ionization coefficient Average number of ionization along carrier trajectory on unit lenght Speed of avalanche build up depends from applied voltages and depletion region depth

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI All mentioned above points for 2D(3D) case areas in pixel: 1.Active central part of pixel 2.Pixel’s perifery 3.Interpixels area 1 and 2 – different diffusion Drift Avalanche build up 1 2

Corsica timing April 2013 E.Popova MEPhI Avalanche build up 3D

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI Avalanche build up 3D

Corsica timing April 2013 E.Popova MEPhI K j – vertical speed u 0 - transversal speed

Corsica timing April 2013 E.Popova MEPhI Jitter should not depends on overvoltage!

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI I throw R L = 8mV/50OhM=160  A Current inside pixel Cpixel Model Corsi with Transversal current expansion Model for current expantion

Corsica timing April 2013 E.Popova MEPhI Waveforms: 1.Single pixel 2.One pixel from 1x1mm2 SiPM the same topology 1 2

Corsica timing April 2013 E.Popova MEPhI 3x3mm 2 4* 3x3mm 2

Corsica timing April 2013 E.Popova MEPhI SPICE N=1000 pixels. Different Cfast Current inside pixel Current on load

Corsica timing April 2013 E.Popova MEPhI 1x1mm 2

Corsica timing April 2013 E.Popova MEPhI SiPM readout SiPM is a system of connected together pixels with one common readout pad Metal buses – delay lines

Corsica timing April 2013 E.Popova MEPhI Out- put 1 2

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI SiPM signal delay dependence on the SiPM chip area

Corsica timing April 2013 E.Popova MEPhI Timing by 5x5mm2 SiPM: a single phe resolution Fig.’s below show the impact of SiPM size(size of one pixel and SiPM itself)on single phe resolution FWHM for SiPMs 1x1mm2(pixel size 25mkm) and 5x5mm2(pixel size 100mkm)

Corsica timing April 2013 E.Popova MEPhI Single µ-cell (100µm x 100µm) time resolution: 89 ps For 1mm x 1mm size SiPM the time response is practically the same as for the single µ-cell

Corsica timing April 2013 E.Popova MEPhI Single pixel response (MEPHI)

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI Main SiPM’s parameters. Jitter vs light intensity. ADVANCED TECHNOLOGY & PARTICLE PHYSICS Proceedings of the 7th International Conference on ICATPP-7 Villa, Olmo, Como, Italy, October 2001 B.Dolgoshein et al.“THE ADVANCED STUDY OF SILICON PHOTOMULTIPLIER”

Corsica timing April 2013 E.Popova MEPhI SUMMARY How we obtain a signal from SiPM 1D case Photoeffect (0 time delta-function) Diffusion in undepleted regions Drift in depleted region Vertical build-up 2D(3D) difference center-edge Transversal expansion Electrical signal propagation Total number of pixels in SiPM Signal readout Pixel position

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI

Corsica timing April 2013 E.Popova MEPhI IRST 1x1 MPPC 1x1

Corsica timing April 2013 E.Popova MEPhI