1. 19-10-2004 1E.Vittone, IEEE-RTSD, ROME Silicon Carbide for Alpha, Beta, Proton and Soft X-Ray High Performance Detectors Ettore Vittone Experimental Physics Department, University of Torino, Italy INFM INFN

2. 19-10-2004 2E.Vittone, IEEE-RTSD, ROME Talk Outline Motivations 4H-SiC Schottky diode manufacture Characterisation and performances X-rays MeV Ions Beta particles Radiation damage Neutrons Conclusions Silicon Carbide for Alpha, Beta, Proton and Soft X-Ray High Performance Detectors

3. 19-10-2004 3E.Vittone, IEEE-RTSD, ROME Physics Dept., University of Modena (F.Nava) Experimental Physics Dept. University of Torino (E.Vittone) Elect Engn & Informat Sci. Dept., Politecnico of Milano (G.Bertuccio) Physics Dept., University of Bologna (A.Cavallini) Material Science Dept., University of Milano (S.Pizzini) Dipartimento di Energetica, University of Florence (S.Sciortino) Alenia Marconi Systems, Roma (I) (C.Lanzieri) Institute of Crystal Growth (IKZ),, Berlin, (D) (G.Wagner) INFM INFN PARTNERS CERN RD50: Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders N37 Radiation Damage Effects I - Solid State, Wednesday, October 20, Spalato M. Bruzzi, INFN Firenze, Italy, On behalf of the CERN RD50 Collaboration

4. 19-10-2004 4E.Vittone, IEEE-RTSD, ROME SiC material from CREE N D -N A =6.8·10 18 cm -3 N D -N A =1.0·10 18 cm -3 N D -N A =2.2·10 15 cm -3 Substrate Buffer layer Epitaxial layer

5. 19-10-2004 5E.Vittone, IEEE-RTSD, ROME Problems and drawbacks thin depletion layer widths defects at the interface of epilayers contacts technology and surface treatments large band gap (3.3 eV) and very low dark current high carrier saturation velocity high breakdown electrical field large thermal conductivity satisfactory electrical homogeneity

6. 19-10-2004 6E.Vittone, IEEE-RTSD, ROME Small Effect of Temperature on Current Lowest Leakage Currents Silicon Carbide Detector Advantages G.Bertuccio Politecnico Milano(2001)

7. 19-10-2004 7E.Vittone, IEEE-RTSD, ROME DIODE MANUFACTURE

8. 19-10-2004 8E.Vittone, IEEE-RTSD, ROME SUBSTRATE CREE 360 m n-type 4H-SiC by CREE (USA) SMP quality: 16-30 micropipes/cm 2 LMP quality: 15 micropipes/cm 2 off-oriented 8° towards 1120

9. 19-10-2004 9E.Vittone, IEEE-RTSD, ROME Günter Wagner http://rd50.web.cern.ch/RD50/2nd-workshop/ EPITAXIAL LAYER Epitaxial wafers purchased from CREE Research. Thickness 30-70 m Institute of Crystal Growth (IKZ), Berlin, Germany (G.Wagner)

10. 19-10-2004 10E.Vittone, IEEE-RTSD, ROME SMP wafer Epilayer thickness: 48.0 ± 0.6 m LMP wafer Epilayer thickness: 48.9 ± 0.8 m Institute of Crystal Growth (IKZ), Berlin, Germany (G.Wagner) SMP LMP Lateral view EPITAXIAL LAYER

11. 19-10-2004 11E.Vittone, IEEE-RTSD, ROME SCHOTTKY DIODE Alenia Marconi Systems, Roma (I) (C.Lanzieri) Si-face Ohmic contact over all the backside of the substrate (C-face): deposition of a multilayer of Ti/Pt/Au (30/30/150 nm) followed by an annealing at 1000°C for 1 min in N 2 /H 2 atmosphere. Schottky contact: Cleaning: sputtering with 200 eV argon ions to remove a thin film of 20 nm on the Si surface of the epilayer; dip in a 10:1 diluted HF solution for 1 min; water rinse; nitrogen blow dry. Deposition: Ni (or Au) was evaporated from an e-gun heated source to a thickness of 200 nm. Circular Ni (or Au) diode dots with a diameter of 1.5,3,5 mm and a guard ring, were obtained using a standard lithography techniques featuring lift-off steps. Annealing (for Ni only): at 800°C for 1 min in N 2 /H 2 atmosphere for the silicide formation (Ni 2 Si) as identified to be by using the X-ray diffraction technique.

12. 19-10-2004 12E.Vittone, IEEE-RTSD, ROME CHARACTERISATION R11 RTSD Poster Session, Thursday, October 21 11:00-12:30, Pola G. Bertuccio, S. Binetti, S. Caccia, R. Casiraghi, A. Castaldini, A. Cavallini, C. Lanzieri, A. Le Donne, F. Nava, S. Pizzini, E. Vittone Physical and Electrical Characterisation of Silicon Carbide for Room and High Temperature Radiation Detectors

13. 19-10-2004 13E.Vittone, IEEE-RTSD, ROME C-V Epilayer from IKZ; Thickness 40 m I-V

14. 19-10-2004 14E.Vittone, IEEE-RTSD, ROME [1] F. Nava et al. Nuclear Instruments and Methods in Physics Research A 437 (1999) 354 [2] A.Castaldini et al. Applied Surface Science 187 (2002) 218-252 [3] F. Nava et al. Nuclear Instruments and Methods in Physics Research A 505 (2003) 645 [4] M.Bruzzi et al. Diamond and Related Materials 12 (2003) 1205 [5] G.Bertuccio et al. Nuclear Instruments and Methods in Physics Research A 522 (2004) 413–419 [6] F.Nava et al., IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 51, NO. 1, FEBRUARY 2004, pag 241 [7] A. Lo Giudice et al. to be published EpilayerThicknes s ( m) Electrode area (cm 2 ) Electro de N D (cm -3 ) J s (pA/cm 2 ) q bn (eV) From I-V From C-V CREE [1,3] 30 3.1 10 -2 Au 2.2 10 15 1.19 1.7 CREE [2] 30 3.1 10 -2 Au 2.0 10 15 1.18 1.38 CREE [3] 30 3.1 10 -2 Au 2.5 10 15 1.03 CREE [4] 50 3.1 10 -2 Au 9.4 10 14 5 10 -11 @ 500 V CREE [5] 70 3.0 10 -4 - 1.2 10 -2 Au 9 10 14 5 10 -13 @ 500 V 1.2 IKZ [6]40 1.8 10 -2 Ni 2 Si4.7- 7.7 10 13 35 10 -10 @ 400 V 1.051.771.84 IKZ [7]40-50 7.0 10 -2 Ni 1.7 10 14 5 10 -12 @ 200 V 1.251.431.75

15. 19-10-2004 15E.Vittone, IEEE-RTSD, ROME IBICC Ion Beam Induced Charge Collection Microscopy Experimental Physics Dept., University of Torino, (I)

16. 19-10-2004 16E.Vittone, IEEE-RTSD, ROME The CCE response is homogeneous for low energy ions where ionisation occurs in the depletion region. More pronounced CCE inhomogeneities in proximity of the buffer layer

17. 19-10-2004 17E.Vittone, IEEE-RTSD, ROME XBICC X-ray Beam Induced Charge Collection Microscopy Experimental Physics Dept., University of Torino, (I)

18. 19-10-2004 18E.Vittone, IEEE-RTSD, ROME Optical microscope image XBIC map of two electrodes XBIC profile

19. 19-10-2004 19E.Vittone, IEEE-RTSD, ROME DLTS and isothermal capacitance transient spectroscopy (ICTS) Physics Department, University of Bologna, (I) (A.Cavallini) NCr/Ti Related to O DLTS at different polarisation conditions todistinguish between in-depth and surface located levels

20. 19-10-2004 20E.Vittone, IEEE-RTSD, ROME DETECTOR PERFORMANCES

21. 19-10-2004 21E.Vittone, IEEE-RTSD, ROME Room and High Temperature X-ray Spectroscopy SiC Detector at 27°C Dept of Electronics Engineering and Information Science, Politecnico di Milano, (G.Bertuccio) Pixel Area = 0.31 mm 2 purchased from CREE Research Noise level = 315 eV FWHM

22. 19-10-2004 22E.Vittone, IEEE-RTSD, ROME = 5.3x10 14 cm -3 Pixel Area = 0.31 mm 2 Current Density of 4H-SiC junctions: < 6 pA/cm 2 up to 100kV/cm (200V) at 24°C < 0.9 nA/cm 2 up to 100kV/cm (200V) at 107°C Room and High Temperature X-ray Spectroscopy

23. 19-10-2004 23E.Vittone, IEEE-RTSD, ROME SiC Detector at 100°CSiC Detector at 27°C Room and High Temperature X-ray Spectroscopy G. Bertuccio et al., Silicon carbide for high resolution X-ray detectors operating up to 100°C, Nucl. Instr. Meth. in Physics Res. A 522 (2004) 413 315 eV FWHM = Equivalent noise energy = 797 eV FWHM Limited by the gate leakage current of the silicon front-end FET No other detector-grade semiconductor is capable of operation at high temperatures

24. 19-10-2004 24E.Vittone, IEEE-RTSD, ROME (MIP) PARTICLE SPECTROSCOPY Dipartimento di Energetica, Università di Firenze (I) (S.Sciortino) From CREE From IKZ N D -N A =8.4·10 13 cm -3 Barrier height 1.8 eV Ideality factor=1.07 Reverse current @ 300 V = 4.4·10 -10 A

25. 19-10-2004 25E.Vittone, IEEE-RTSD, ROME (MIP) PARTICLE SPECTROSCOPY Pedestal Number of e/h per m for MIPs = 55 Detector thickness = 40 m SNR=6

26. 19-10-2004 26E.Vittone, IEEE-RTSD, ROME ION SPECTROSCOPY He ion spectra @150 V bias voltage Energy Loss of He ions in SiC The electron-hole pair generation energy ε SiC SiC has been experimentally determined by comparing the spectral responses of several 4H-SiC Schottky diodes and a Si nuclear detector (ε Si =3.62 eV) at room temperature using He ions of different energies.

27. 19-10-2004 27E.Vittone, IEEE-RTSD, ROME ALPHA PARTICLE SPECTROSCOPY Plutonium ( 239 P): Americium ( 241 Am): Curium ( 244 Cm): Peaks: 5.16 MeV (73.1 %); 5.14 MeV (15.0%); 5.10 MeV (11.8 %); others Peaks: 5,49 MeV (85.2 %); 5.44 MeV (12.8 %): 5.39 MeV (1.4 %); others Peaks: 5.80 MeV (77.4 %); 5.76 MeV (23.0 %); others 15 ± 3 keV = Energy Resolution = 70 ± 15 keV 25 mm 2 Si detector7 mm 2 4H-SiC detector

28. 19-10-2004 28E.Vittone, IEEE-RTSD, ROME

29. 19-10-2004 29E.Vittone, IEEE-RTSD, ROME Depletion Region

30. 19-10-2004 30E.Vittone, IEEE-RTSD, ROME Depletion Region FAST DRIFT COMPLETE COLLECTION DIFFUSION

31. 19-10-2004 31E.Vittone, IEEE-RTSD, ROME Drift+Diffusion Model dxxp dE dx dE Q d w w 0

32. 19-10-2004 32E.Vittone, IEEE-RTSD, ROME L p =(7.0±0.3) m D p = 3 cm 2 /s p = 160 ns dxxp dE dx dE CCE d w w 0 In virgin samples, L is constant and p+(x)=sinh[(d-x)/L]/sinh[(d-w)/L]

33. 19-10-2004 33E.Vittone, IEEE-RTSD, ROME RADIATION DAMAGE

34. 19-10-2004 34E.Vittone, IEEE-RTSD, ROME 24 GeV proton irradiation FLUENCE = 9.37 x 10 13 p/cm 2

35. 19-10-2004 35E.Vittone, IEEE-RTSD, ROME 8.2 MeV electrons -rays from a 60 Co source Ion probe:4.14 MeV alpha particles

36. 19-10-2004 36E.Vittone, IEEE-RTSD, ROME C/VAlpha spectroscopy SampleN eff (cm 3 ) eV) nL ( m) Virgin2.18E151.71.198.57 Proton irradiated 10 14 p/cm 2 1.43E151.721.181.0 Virgin2.49E151.031.049.5 Electron irradiated 2 Mrad 2.69E151.061.042 Electron irradiated 20 Mrad 1.67E151.131.0361 Virgin2.49E151.031.0349.9 Gamma irradiated 20 Mrad 2.28E151.031.0335 Gamma irradiated 40 Mrad 2.21E151.031.0341.6

37. 19-10-2004 37E.Vittone, IEEE-RTSD, ROME DLTS Physics Department, University of Bologna, (I) (A.Cavallini) PHOTOLUMINESCENCE Material Science Dept., University of Milano Bicocca, (S.Pizzini) Virgin:convolution of two donor-acceptor pair recombinations, the one at highest energy related to a transition between a N level and the B level at about Ev+0.35 eV and the one at lowest energy related to a transition between a N level and the B level at about Ev+0.65 eV; emission at about 1.8 eV: present only in the sample submitted to the highest doses. Evolution of DLTS spectra of electron irradiated 4H SiC detectors with irradiation fluence. The concentration of traps (S1 – S5) grows linearly with the irradiation dose, while that of S0 is constant.

38. 19-10-2004 38E.Vittone, IEEE-RTSD, ROME Preliminary neutrons detection measurements TAPIRO: reactor located at ENEA Casaccia Research Centre, Roma. Epithermal column designed and realized in view of BNCT (Boron Neutron Capture Therapy) treatments (special application: brain tumours) Total neutron flux @ maximum reactor power (5 kW): 1.15 10 9 cm 2 s -1. Experimental Physics Dept., University of Torino, (I) (C.Manfredotti, A.Lo Giudice)

39. 19-10-2004 39E.Vittone, IEEE-RTSD, ROME LiF 6 Li(n, ) 3 H 6 Li 4 He E=2.05 MeV 3 H E=2.73 MeV SiC detector Detector Depletion layer > 30 m Thickness: 50 m neutron Neutron detectors 4 He 3 H Penetration in SiC: 4 He = 4.8 m 3 H=27.4 m

40. 19-10-2004 40E.Vittone, IEEE-RTSD, ROME 7 mm 2 electrode No changes up to a fluence of 10 13 neutroni/cm 2 2.73 MeV 1.8 mm 2 electrode Experimental Physics Dept., University of Torino, (I) (C.Manfredotti, A.Lo Giudice)

41. 19-10-2004 41E.Vittone, IEEE-RTSD, ROME CONCLUSIONS N-type 4H-SiC epitaxial Schottky diodes were manufactured doping concentration > 5·10 13 cm -3 low reverse current for T 25°C X-ray detection at high temperature Beta (MIP) detection (active region thickness = 40 m, SNR=6) Ion spectroscopy (FWHM=70keV, A=7 mm 2 ) Complete charge collection at the depletion layer in strongly irradiated samples. Neutron detection