Latest est measu asureme rements ts of LGAD D dio iodes - - PowerPoint PPT Presentation

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Latest est measu asureme rements ts of LGAD D dio iodes fabric ricated ted at IMB-CN CNM

9th

th

“Trento” Workshop on Advan vance ced d Silicon

• n Radi

diat ation ion Dete tect ctors

• rs

Vir irgin inia ia Greco eco -

IMB-CNM CNM, , Barc rcelona na (Spain in) P.

• P. Fern

rnández Martí rtínez, , M. Baselga ga, , S. Hid idalgo go, Giu iulio io Pel Pellegrin rini, , D.

• D. Quirion

irion

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Introduction PiN detectors used for tracking applications Proportional response Good efficiency Segmentation technologically available (strips and pixels)

• After irradiation  Radiation Damage

 Worsening of signal to noise ratio (S/N) Need to improve performances after irradiation of PiN diode for radiation detection.

Track cking ing Silic ilicon Detecto tectors rs  PiN iN Dio iodes

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Exploit avalanche phenomenon of a pn junction polarized in reverse mode. LGAD = Low Gain Avalanche Diode Diodes with internal gain are more radiation hard Charge multiplication compensates charge loss due to trapping; Higher electric field => Shorter collection times => Lower trapping probability Have higher signal to noise ratio (S/N) => Better spatial resolution Low gain (<10)  Good for particle physics High gain => Higher noise (lower S/N) => Longer collection times => Higher trapping probability

Avalanch lanche Dio iodes wit with Low

• w

Intern ernal al Gain in

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

The goal: a diode with multiplication working in linear mode. Starting point : PiN-PAD diode with an area of 5mm x 5mm. Structure: highly resistive p-type substrate n+ well for the cathode p diffusion under the cathode => enhance electric field => multiplication layer

p type (π) substrate P type multiplication layer n+ cathode p+ anode

Struc uctur ture of L LGAD

The doping profile

• f this layer is a

very critical technical parameter

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Electric Field @ 400 V

Two regions  different junctions: Central area  uniform electric field, high enough to activate mechanism

• f charge multiplication

Periphery N+ P N π

𝑾𝑪𝑬|𝐃𝐟𝐨𝐮𝐬𝐛𝐦 ≪ 𝑾𝑪𝑬|𝐔𝐟𝐬𝐧𝐣𝐨𝐛𝐮𝐣𝐩𝐨

We want:

Design ign

• f the

Edge ge Termina rmination tions

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona p type (π)substrate n+ cathode p+ anode

JTE

p type multiplication layer

𝑾𝑪𝑬|𝐃𝐟𝐨𝐮𝐬𝐛𝐦 ≪ 𝑾𝑪𝑬|𝐔𝐟𝐬𝐧𝐣𝐨𝐛𝐮𝐣𝐩𝐨

We want:

Low doping n well in the periphery

• f the cathode

higher voltage capability

PiN Diode with JTE Junction Termination Extension

2D Simulation: Lower electric field peak

Design ign

• f the

Edge ge Termina rmination tions

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona High Electric Field peak at the junction

Non-Irradiated Irradiated at Φeq=1x1015 cm-2

Curves @ 600 V

PiN  electric field at the junction higher after irradiation LGAD  electric field at the junction  after irradiation = before irradiation

Simu imula latio ion

• f Irrad

radia iated ted Devic vices es

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

100 200 300 400 500 600 1000 2000 3000 4000

Noise [e] Bias Voltage [V]

W8_E10 W8_H11 2328-10

ENC

100 200 300 400 500 600 50000 100000 150000 200000 250000 300000

Most Probable Charge [e] Bias Voltage [V]

W8_E10 W8_H11 2328-10

90Sr most probable charge before irradiation

Charge collection measurements of MIPs with 90Sr source Before irradiation: Improvement of signal  a factor 8 at 300V After irradiation: no significant increase of the noise

Effec ects ts

• f Radia

diation tions

Performed at the “Jozef Stefan” Institut, in Ljubljana, Slovenia

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Optical window (passivated)

Collector Ring (metallized)

5 mm 1mm

Devices with active area of 5mmx5mm Window in the cathode metallization for light source characterization

Mask layout

Fabric ricat atio ion Layou ayout

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Wafer Number P-layer Implant (E = 100 keV) Substrate features Expected Gain 1-2 1.6 × 1013 cm-2 HRP 300 (FZ; ρ>10 KΩ·cm; <100>; T = 300±10 µm) 2 – 3 3-4 2.0 × 1013 cm-2 HRP 300 (FZ; ρ>10 KΩ·cm; <100>; T = 300±10 µm) 8 – 10 5-6 2.2 × 1013 cm-2 HRP 300 (FZ; ρ>10 KΩ·cm; <100>; T = 300±10 µm) 15 7 (---) PiN Wafer HRP 300 (FZ; ρ>10 KΩ·cm; <100>; T = 300±10 µm) No Gain

Various fabrication runs to improve the characteristics of the LGAD devices. Latest run: High resistivity p-type substrate; 300μm thick; 3 couples of wafers with increasing p-layer doping A PiN wafer for reference

Fabric ricat atio ion Run uns

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

I-V curves  3 different p-doping wafers and PiN wafer Increasing current, but plateau reached; High breakdown.

Wafer Number P-layer Implant (E = 100 keV) W1 1.6 × 1013 cm-2 W3 2.0 × 1013 cm-2 W5 2.2 × 1013 cm-2 W7 (---) PiN Wafer

Ele lectr tric ical al Cha Characteriz cterization tion

I-V Curves

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Ele lectr tric ical al Cha Characteriz cterization tion

I-V curves Abrupt transition at ~40V÷50V At~50V the depletion zone reaches the device edge huge surface current

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Wafer 1  1.6 × 1013 cm-2 Current levels spreading throughout the wafer (from < 10 µA to > 1 mA). Most detectors  [10÷100 µA] Percentage of detectors on wafer 1 distinguished for current ranges at 500V polarization

Wafer r 1 - Performan formance ce St Statist tistic ics

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

100 200 300 400 500 1E-7 1E-6 1E-5 Wafer 1 - LGAD D8

Current (A) Reverse bias (V) 20C 10C 0C

• 10C
• 20C
• 30C
• 40C

I-V Curves at different temperatures

I-V curves  at different temperatures (from 20ºC down to -40ºC)

Wafer r 1

• Ele

lectric trical al Ch Character cteriz izatio ation

We suppose there is a big contribution of the surface current Little reduction of the current with the temperature

@ 500V

• 40
• 30
• 20
• 10

10 20 3,0µ 4,0µ 5,0µ 6,0µ 7,0µ

Current @ 500V (A) Temperature (C)

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

1/C2-V Curve  A detector from wafer 1

VFD ~ 40V

T = 20° C f = 10 kHz

Wafer r 1

• Ele

lectric trical al Ch Character cteriz izatio ation

C ~ 20÷24 pF VFD ~ 40V (Method of intercept)

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Multiplication factor measured with tri-alpha radiation source  (239Pu/241Am/244Cm) Non-multiplied signal Multiplied signal Irradiation from the back

Wafer r 1

• Ch

Charge ge Co Coll llection tion

T = -22ºC

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

𝐇𝐛𝐣𝐨@𝐖 = 𝐃𝐟𝐨𝐮𝐬𝐛𝐦 𝐐𝐟𝐛𝐥 𝐃𝐢𝐛𝐨𝐨𝐟𝐦@𝐖 𝐃𝐟𝐨𝐮𝐬𝐛𝐦 𝐐𝐟𝐛𝐥 𝐃𝐢𝐛𝐨𝐨𝐟𝐦𝐎𝐩 𝐧𝐯𝐦𝐮 Gain ~ 2,3 ÷ 3,5

Wafer r 1

• Gain

in

T = -22ºC

Wafer Num P-layer Implant (E=100 keV) Expected Gain 1-2 1.6 × 1013 cm-2 2 – 3

As expected

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Wafer r 1

• Gain

in

Gain measured for LGAD detector at different temperatures: Higher temperature  lower gain @ -22ºC Gain ~ 2,3 ÷ 3,5 @ +19ºC Gain ~ 2,0 ÷ 3,0

200 400 600 800 1000 1200 0,5 1,0 1,5 2,0 2,5 3,0 3,5

Gain Reverse Bias [V]

+19C

• 22C

LGAD Gain

Run 7062 Wafer1 LGAD K8

p-well doping 1.6 × 1013 cm-2

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

the structure of the LGAD (Low Gain Avalanche Diode): multiplication layer; design of the edge terminations; the electrical characterization of LGAD detectors with different p-doping of the multiplication layer and at different temperatures; the results of the charge collection measurements performed

• n the LGAD detector with lower p-doping (1.6 × 1013 cm-2) of the

multiplication layer; the gain (at different temperatures) of LGAD detectors with lower p-doping. We have presented:

Co Conclu lusio ions

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Further characterization with MIPs of LGAD with low doped multiplication layer. Electrical and charge collection measurements of detectors with higher p-doping

• f the multiplication layer.

 Ongoing Study of detectors after irradiation.  We have already sent LGAD diodes to be irradiated with protons (in Los Alamos). Application of the multiplication mechanism to segmented detectors (microstrips and pixels).  See following talk by M.Baselga New fabrication run, with a new geometry that includes isolation structures (p-stop, collector ring, channel stop). Realization of low gain thin (~200μm) detectors.

Fut utur ure e Work

Collector Ring

9th “Trento” Workshop on Advanced Silicon Radiation Detectors

Genova, February 26-28, 2014 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Trackers for high energy physics experiments. Direct detection of soft x-rays (<2KeV)  Syncrotron radiation experiments More…

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• u !