High. Thickness. epitaxial Silicon. Carbide Detectors. INFN - Gruppo V 2009

Transcription

1 INFN - Gruppo V Proposta di nuovo esperimento per il triennio High Thickness epitaxial Silicon Carbide Detectors Sezioni INFN di Milano - Bologna - Catania

2 Outline A general introduction on Silicon Carbide SiC detectors: International R&D INFN Research Activity on SiC Radiation Detectors HiTSiC Proposal

3 A General Introduction on Silicon Carbide

4 SiC politypes 3C-SiC (E G = 2.2 ev) 4H-SiC (E G = 3.3 ev) 6H-SiC (E G = 3 ev)

5 Wide Bandgap E G =3.2 ev Room & High temperature operation SiC properties x 10 x 2.5 x 2 Si GaAs 4H-SiC High saturation velocity v S = 200 µm/ns High frequency/speed devices 0 E g (ev) E c (MV/cm) λ th (W/cmK) V s (10 7 cm/s) High Critical Field E C = 2 MV/cm High Voltage devices High thermal conductivity High Power devices

6 High Performance SiC Electron Devices...a reality

7 SiC High Performance Electron Devices The highest V B diode Kansai corp. Power MOSFET: 5 kv - 88 mω cm 2 Reverse Voltage [kv] V B = 19 kv Current [ na ] Rockwell International High Power X-Band MESFET f T f=14.5 T GHz, GHz, f MAX f =38 MAX =38 GHz GHz I Dmax I = Dmax ma, ma, V DSmax =150V DSmax =150V Gain: Gain: db 2 GHz GHz

8 Silicon Carbide Technology a continuous progress

9 Power Device Performance SiC vs. Si 4H-SiC MOSFET 5 kv - 88 mω cm 2 Kansay Co (Japan)- CREE Inc. (USA) 4H-SiC BJT 1.8 kv - 11 mω cm 2 CREE Inc. (USA) 4H-SiC JFET 600 V - 5 mω cm 2 Rockwell (USA)

10 April 2001: first commercial SiC Diode

11 2006: SiC Ultrafast Power Schottky Diodes

12 2006: SiC Power MESFET s

13 12 kva SiC Inverter

14 June 2006: R&D investments

15 Conclusions on SiC status SiC knowledge and technology is continuously growing Industrial R&D are running SiC power device gives better performance than Si counterpart High performance SiC diodes & MESFET s on market Material quality is continuously improving

16 Silicon Carbide Radiation Detectors Motivation International R&D INFN R&D

17 Wide Bandgap High Schottky / pn barriers Low thermally generated currents No cooling required High temperature Silicon Carbide Properties benefits for radiation detectors ev 2 MV/cm 3.8 W/cmK Si GaAs 4H-SiC 200 µm/ns 1 0 High Critical Field High Bias Voltage Reduced Soft Breakdown No guard rings necessity E g (ev) E c (MV/cm) High thermal conductivity Easy T control FEE cooling λ th (W/cmK) V s (10 7 cm/s) High saturation velocity short transit time Fast signals Low trapping probability

18 SiC Detectors European Research Activity

19 Westinghouse SiC Detectors CREE Inc. Reactor core SiC detector Dulloo, Ruddy et al., IEEE Trans. Nucl. Science 46, 1999

20 Naval Research Laboratory Brookhaven National Laboratory CREE Inc.

21 INFN Research Activity on SiC Radiation Detectors

22 INFN SiCPOS experiment ( ) Pad detectors Microstrips SiC wafers: Pixel detectors SiC Technology:

23 Results: Detector Leakage Current Density Schottky contact - Au n - epilayer 5x µm n+ buffer 1 µm n+ substrate µm ohmic contact - Ti/Pt/Au Current density [ A / cm 2 ] Room Temperature CdTe CdZnTe Silicon 1000 SI LEC GaAs (pn) VPE GaAs (SJ) +127 C SiC Mean electric field [ kv / cm ] 10-5 Si / GaAs 1 na/cm SiC 1 pa/cm 2

24 SiC Pixels Detectors Performance RT Leakage Current vs. Bias Pixel Reverse Current 10 fa 1 fa ENC PW 300 K 27 C 400 x 400 µm 2 PIXEL 200 x 200 µm 2 PIXEL Reverse Voltage [ V ] < 10 fa < 1 fa The Front-End Issue! 0.1 fa The Front-End Issue! 1 [ fa] τ [ s] [ e r. m..] = I peak µ s Number of pixels ± 0.1 e ± 0.1 e Pixel Noise [ electrons r.m.s. ] + 27 C II fa fa ENC ENC (τ=20µs) < 1 ee - - rms rms Sub-Electron Noise Detectors (Fano (Fano limited) limited) G. Bertuccio, S. Caccia, R. Casiraghi, C. Lanzieri IEEE Trans. Nucl. Sci., 53 n.4, August 2006, pp

25 Ultra Low Noise CMOS Charge Amplifier for SiC Detectors S ID [ A 2 Hz -1 ] CMOS Preamplifier chip 1 / f k 10k f [Hz] 100k 1M LF Noise modelling 300µA 100µA 30µA 10µA G. Bertuccio and S. Caccia, E N C [ e- r.m.s. ] e e - r.m.s. - r.m.s Shaping Time [ µs ] Measured ENC e e - r.m.s. - r.m.s. Invited talk at the 11 th Symposium on Radiation Measurements and Applications, Ann Arbor, Michigan, USA, May 23-25, 2006 Submitted to NIM A, May 2006 ENC [ electrons r.m.s. ] τ = 12 µs 7.6 e e - - // µw µw ee - - // mw mw 30µW 100µW 1mW 10mW Preamplifier Power Consumption

26 Low- Noise Charge Preamplifiers A New state of the Art ENC [e- r.m.s.] Power [ mw/ch ] Technology Reference CMOS 0.35 µm This work CMOS 0.35 µm This work 9 11 CMOS 1.2 µm BNL [1] 14 8 CMOS 0.35µm BNL [2] 15 6 CMOS 0.5 µm LBL [3] CMOS 0.5 µm Nova [4] 29 - CMOS 1.2 µm Caltech [5]

27 How our Research Activity and Results are seen worldwide? Invited Talks at International Conferences G. Bertuccio " Front-end Amplifiers and ASIC s in Sub-micron CMOS and BiCMOS Technologies for Charge Measurements" Nuclear Science Sympsium and Medical Imaging Conference, October 2003, Portland, USA. G. Bertuccio, R. Casiraghi, F. Nava, M. Bruzzi "Performance of Silicon Carbide Radiation Detectors " 13th International Workshop on Room Temperature Semiconductor Detectors and Associated Electronics, October 2003, Portland, USA. G. Bertuccio "Prospects for Energy Resolving X-ray imaging with Compound Semiconductor Pixel Detectors" 6th International Workshop on Radiation Imaging Detectors, July 2004, Glasgow, Scotland. G. Bertuccio et al. "Silicon Carbide for Alpha, Beta, Ion and soft X-ray High Performance Detectors" 5th European Conference on Silicon Carbide and Related Materials, 31 August-4 September 2004, Bologna, Italy. G. Bertuccio, S. Caccia "Challenges in the Readout Electronics for Room Temperature Semiconductor Radiation Detectors " 14th International Workshop on Room Temperature Semiconductor Detectors and Associated Electronics, October 2004, Rome, Italy. G. Bertuccio, S. Caccia Ultra Low Noise Front-End and ASIC for X-ray Spectroscopy" 11th Symposium on Radiation Detection and Applications, May 2006, Ann Arbor, USA.

28 Present Limit of SiC detectors Schottky contact - Au Depth of depletion layer X D X D n - epilayer 5x µm X D V N R d reverse bias dopant concentration n+ buffer 1 µm n+ substrate µm ohmic contact - Ti/Pt/Au Thick depletion layer N d =5x 10 14, V R =300 V X D = 25 µm ( X D = 70 µm V R = 2.3 kv ) High detection efficiency ( X-rays) High peak/valley ratio (X-rays) Higher signal ( α, e - ) Thick X D requires Low capacitance lower ENC, τ opt Thick Thick // High High purity purity // Defect Defect free free epitaxial layers layers (>100 (>100 µm) µm) Low Low residual residual doping doping N d ( d ( < cm cm -3-3 ))

29 Challenges and open issues for SiC detectors R&D Increase the epitaxial layer thickness Is it possible to grow µm? How to increase the process growth rate? How the crystal defectivity depends on the growth rate? Decrease the residual doping What is the origin of the residual doping? Where does the dopants come from? Is it possible to reach cm -3 with the available reactors / processes or new reactor/process must be introduced? Physics of thick-high purity SiC epitaxial detectors How large will be the leakage current (noise!) in thick SiC detectors? What the values of the electron/hole mean drift length at electric fields E<10kV/cm? What will be the radiation resistance of thick SiC detectors?

30 INFN - Gruppo V Proposta di nuovo esperimento per il triennio High Thickness epitaxial Silicon Carbide Detectors Research group Collaborations Research Activity & Milestones

31 Research Team G. Bertuccio (RN), S. Caccia, E. Gatti, S. Riboldi, S. Masci, M. Sampietro INFN - Milano and Politecnico di Milano (Giuseppe.Bertuccio@polimi.it) F. Nava, M. Bagni, T. Corazzari, P. Errani INFN Bologna and University of Modena (nava.filippo@unimo.it) G. Foti, D. Puglisi INFN and University of Catania (Gaetano.Foti@ct.infn.it) Industrial & other collaborations

32 HiTSiC: overcoming SiC R&D limits Limits of previous SiC detectors R&D Wafer supplier: CREE Inc. (USA) Not the best SiC wafers available Not possibility to change epi-growth specification Epitaxy from IKZ (Germany): low epi-specification control Overcoming limits by means of National wafer supplier: LPE-ETC R&D on SiC epitaxial growth at LPE-ETC Strong feedback with LPE-ETC

33 LPE-ETC: R&D Industrial collaboration

34 LPE-ETC: Epitaxial Reactors & Processes

35 LPE-ETC collaboration Growth rate (µm/hr) T dep =1650 C C/Si=1.0 HCl 40 T dep =1550 C 20 No HCl C/Si=1.5 Silicon precipitates Si/H 2 %

36 SELEX: R&D Industrial collaboration

37 A Complete SiC Detectors R&D in Italy Strong Points Availability of the highest material quality High Thickness Epitaxial Layers ( µm) Lowest residual doping (10 13 cm -3 ) Device to Material Feedback Material Wafer Production Characterisation Detector/FEE design & fabrication Detector/FEE characterisation Current [ A ] 10-6 t=127 C t=47 C t=24 C t=67 C t=107 C t=87 C Forward Voltage [ V ] kev 241 Am Counts kev RMS (nm) HCl process STD process 5 x 5 µm Energy [ kev ] INFN Milano & Bologna Growth rate (µm/h) INFN Catania & IMM Feedback

38 HiTSiC Research Activity INFN INFN Milano Milano INFN INFN Catania Catania TASKS INFN INFN Bologna Bologna DETECTOR DESIGN DETECTOR DESIGN FRONT END ELECRONICS DESIGN FRONT END ELECRONICS DESIGN DETECTOR ELECTRICAL CHAR. DETECTOR ELECTRICAL CHAR. X-RAY SPECTROSCOPIC CHAR. X-RAY SPECTROSCOPIC CHAR. SiC GROWTH SiC GROWTH SiC MATERIAL SiC MATERIAL CHARACTERIZATION CHARACTERIZATION (DLTS RBS-Channeling, Low (DLTS RBS-Channeling, Low Temperature PL) Temperature PL) JUNCTION DEVELOPMENT. JUNCTION DEVELOPMENT. DETECTOR CHARACTERIZATION DETECTOR (α, β). CHARACTERIZATION (α, β). RADIATION RESISTANCE RADIATION RESISTANCE MILESTONES TECHNOLOGICAL: - Growth of SiC wafers with High Thickness / High Purity / Low defect density - Ultra Thin Ultra Low leakage Schottky Junction - High Yield Large Area Detector Fabrication SCIENTIFIC & APPLIED: - High Resolution Wide Temperature Detectors - SiC Crystal knowledge (imputities/deep&shallow levels/traps/defects) - Custom Ultra-low Noise Front-End Electronics