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

Genova, February 26-28, 2014 9 th “Trento” Workshop on Advanced Silicon Radiation Detectors Latest est measu asureme rements ts of LGAD D dio iodes fabric ricated ted at IMB-CN CNM Vir irgin inia ia Greco eco - IMB-CNM CNM, , Barc rcelona na (Spain in) P. Fern P. rnández Martí rtínez, , M. Baselga ga, , S. Hid idalgo go, Giu iulio io Pel Pellegrin rini, , D. D. Quirion irion 9 th th “Trento” Workshop on Advan vance ced d Silicon on Radi diat ation ion Dete tect ctors ors Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Genova, February 26-28, 2014 9 th “Trento” Workshop on Advanced Silicon Radiation Detectors Track cking ing Silic ilicon Detecto tectors rs  PiN iN Dio iodes 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. Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Genova, February 26-28, 2014 9 th “Trento” Workshop on Advanced Silicon Radiation Detectors Avalanch lanche Dio iodes wit with Low ow Intern ernal al Gain in 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 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Genova, February 26-28, 2014 9 th “Trento” Workshop on Advanced Silicon Radiation Detectors Struc uctur ture of L LGAD 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 n+ cathode The doping profile of this layer is a very critical P type multiplication layer technical parameter p type ( π ) substrate p+ anode Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Genova, February 26-28, 2014 9 th “Trento” Workshop on Advanced Silicon Radiation Detectors Design ign of the Edge ge Termina rmination tions Two regions  different junctions: Central area  uniform electric field, high enough to activate mechanism of charge multiplication Electric Field @ 400 V Periphery N + N P π 𝑾 𝑪𝑬 | 𝐃𝐟𝐨𝐮𝐬𝐛𝐦 ≪ 𝑾 𝑪𝑬 | 𝐔𝐟𝐬𝐧𝐣𝐨𝐛𝐮𝐣𝐩𝐨 We want: Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Genova, February 26-28, 2014 9 th “Trento” Workshop on Advanced Silicon Radiation Detectors Design ign of the Edge ge Termina rmination tions 𝑾 𝑪𝑬 | 𝐃𝐟𝐨𝐮𝐬𝐛𝐦 ≪ 𝑾 𝑪𝑬 | 𝐔𝐟𝐬𝐧𝐣𝐨𝐛𝐮𝐣𝐩𝐨 We want: Low doping n well in the periphery of the cathode n+ cathode higher voltage capability p type multiplication Junction Termination Extension layer JTE p type ( π )substrate p+ anode PiN Diode with JTE 2D Simulation: Lower electric field peak Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Genova, February 26-28, 2014 9 th “Trento” Workshop on Advanced Silicon Radiation Detectors Simu imula latio ion of Irrad radia iated ted Devic vices es Curves @ 600 V Irradiated Non-Irradiated at Φ eq =1x10 15 cm -2 High Electric Field peak at the junction PiN  electric field at the junction higher after irradiation LGAD  electric field at the junction  after irradiation = before irradiation Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Genova, February 26-28, 2014 9 th “Trento” Workshop on Advanced Silicon Radiation Detectors Effec ects ts of Radia diation tions Charge collection measurements of MIPs with 90 Sr source 300000 Most Probable Charge [e] Performed at the 250000 “ Jozef Stefan” Institut, in Ljubljana, 200000 Slovenia 90 Sr most probable charge before irradiation 150000 W8_E10 100000 W8_H11 Before irradiation: 50000 2328-10 Improvement of signal 0 0 100 200 300 400 500 600  a factor 8 at 300V Bias Voltage [V] 4000 ENC 3000 Noise [e] After irradiation: no 2000 significant increase of W8_E10 1000 W8_H11 the noise 2328-10 0 0 100 200 300 400 500 600 Bias Voltage [V] Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Genova, February 26-28, 2014 9 th “Trento” Workshop on Advanced Silicon Radiation Detectors Fabric ricat atio ion Layou ayout Devices with active area of 5mmx5mm Window in the cathode metallization for light source characterization Optical window (passivated) 5 mm 1mm Collector Ring (metallized) Mask layout Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Genova, February 26-28, 2014 9 th “Trento” Workshop on Advanced Silicon Radiation Detectors Fabric ricat atio ion Run uns Various fabrication runs to improve the characteristics of the LGAD devices. Latest run: High resistivity p-type substrate; 300 μ m thick; 3 couples of wafers with increasing p-layer doping A PiN wafer for reference Wafer P-layer Implant Substrate features Expected Gain Number (E = 100 keV) HRP 300 (FZ; ρ >10 K Ω ·cm; 1-2 1.6 × 10 13 cm -2 2 – 3 <100>; T = 300±10 µm) HRP 300 (FZ; ρ >10 K Ω ·cm; 3-4 2.0 × 10 13 cm -2 8 – 10 <100>; T = 300±10 µm) HRP 300 (FZ; ρ >10 K Ω ·cm; 5-6 2.2 × 10 13 cm -2 15 <100>; T = 300±10 µm) HRP 300 (FZ; ρ >10 K Ω ·cm; 7 (---) PiN Wafer No Gain <100>; T = 300±10 µm) Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Genova, February 26-28, 2014 9 th “Trento” Workshop on Advanced Silicon Radiation Detectors Ele lectr tric ical al Cha Characteriz cterization tion I-V curves  3 different p-doping wafers and PiN wafer Increasing current, but plateau reached; High breakdown. I-V Curves Wafer P-layer Implant Number (E = 100 keV) W1 1.6 × 10 13 cm -2 W3 2.0 × 10 13 cm -2 W5 2.2 × 10 13 cm -2 W7 (---) PiN Wafer Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Genova, February 26-28, 2014 9 th “Trento” Workshop on Advanced Silicon Radiation Detectors 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 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Genova, February 26-28, 2014 9 th “Trento” Workshop on Advanced Silicon Radiation Detectors Wafer r 1 - Performan formance ce St Statist tistic ics Wafer 1  1.6 × 10 13 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 Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Genova, February 26-28, 2014 9 th “Trento” Workshop on Advanced Silicon Radiation Detectors Wafer r 1 - Ele lectric trical al Ch Character cteriz izatio ation I-V curves  at different temperatures (from 20ºC down to -40ºC) Little reduction of the current with the temperature I-V Curves at different temperatures 1E-5 7,0µ 20C 10C @ 500V 0C 6,0µ -10C -20C Current @ 500V (A) -30C Current (A) -40C 5,0µ 1E-6 4,0µ Wafer 1 - LGAD D8 3,0µ 1E-7 0 100 200 300 400 500 -40 -30 -20 -10 0 10 20 Reverse bias (V) Temperature (C) We suppose there is a big contribution of the surface current Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Genova, February 26-28, 2014 9 th “Trento” Workshop on Advanced Silicon Radiation Detectors Wafer r 1 - Ele lectric trical al Ch Character cteriz izatio ation 1/C 2 -V Curve  A detector from wafer 1 VFD ~ 40V C ~ 20÷24 pF V FD ~ 40V (Method of intercept) T = 20 ° C f = 10 kHz Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona

Genova, February 26-28, 2014 9 th “Trento” Workshop on Advanced Silicon Radiation Detectors Wafer r 1 - Ch Charge ge Co Coll llection tion Multiplication factor measured with tri-alpha radiation source  ( 239 Pu/ 241 Am/ 244 Cm) Multiplied signal Non-multiplied signal Irradiation from the back T = -22ºC Centro Nacional de Microelectrónica Instituto de Microelectrónica de Barcelona