1. 7 th RD50 Workshop CERN Geneva November 14-16 2005 Università degli Studi Università degli Studi di Perugia di Perugia 1 Radiation Hardness of Minimum Ionizing Particle Detectors Based on SiC p + n Junctions Francesco Moscatelli 1,2*, Andrea Scorzoni 1,2, Antonella Poggi 2, Mara Bruzzi 3, Silvio Sciortino 3, Stefano Lagomarsino 3, Günter Wagner 4 and Roberta Nipoti 2 1 DIEI and INFN, University of Perugia, via G. Duranti 93, 06125 Perugia, Italy 2 CNR- IMM Sezione di Bologna, via Gobetti 101, 40129 Bologna, Italy 3 Dipartimento di Fisica, Polo Scientifico di Sesto Fiorentino,Via Sansone 1 Firenze Italy 4 Institut für Kristallzüchtung, D-12489 Berlin, Germany. This work was partially supported by the INFN SiCPOS project and by the CERN RD50 Collaboration

2. 7 th RD50 Workshop CERN Geneva November 14-16 2005 Università degli Studi Università degli Studi di Perugia di Perugia 2 Outline Introduction Technological process Summary of measurements on unirradiated devices I/V - C/V measurements on irradiated devices CC measurements on irradiated devices Conclusions and future developments

3. 7 th RD50 Workshop CERN Geneva November 14-16 2005 Università degli Studi Università degli Studi di Perugia di Perugia 3 Introduction 300 e - at 600 V after 7x10 15 n/cm 2 ! S. Sciortino et al. “Effects of heavy proton and neutron irradiations on epitaxial SiC Schottky diodes”, NIM A 552 (2005) 138-145.

4. 7 th RD50 Workshop CERN Geneva November 14-16 2005 Università degli Studi Università degli Studi di Perugia di Perugia 4 SiC Process: p + /n Ion implantation Al + @ 300°C Annealing 1600°C 30 min p + doping (0.4  m) = 4  10 19 cm -3 p - doping (0.6  m) = 5  10 17 cm -3 Front:Al (350 nm) / Ti (80 nm) deposition Back: Ni Epi (55  m) doping: 2  10 14 cm -3 Growth by IKZ of Berlin Annealing 1000°C in vacuum 2 min nn n+n+

5. 7 th RD50 Workshop CERN Geneva November 14-16 2005 Università degli Studi Università degli Studi di Perugia di Perugia 5 Mask design DiodeDiameter (  m) JTE (  m) D1250200 D2400200 D3600200 D4800200 D51000200 D6400No D7150No S1 Schottky 400No 31 diodes in every die

6. 7 th RD50 Workshop CERN Geneva November 14-16 2005 Università degli Studi Università degli Studi di Perugia di Perugia 6 I-V and C-V measurements on unirradiated p + /n diodes Theoretical limit for this device  6 kV Epi doping not uniform (average value 2  10 14 cm -3 ) The depletion voltage is near 220- 250 V

7. 7 th RD50 Workshop CERN Geneva November 14-16 2005 Università degli Studi Università degli Studi di Perugia di Perugia 7 CC measurements on reference 3000 e - @ 200 V and 3100 e - @ 600 V for diode with D=1 mm

8. 7 th RD50 Workshop CERN Geneva November 14-16 2005 Università degli Studi Università degli Studi di Perugia di Perugia 8 Irradiation with neutrons Irradiation with 6 different fluences in the range 10 14 -10 16 1 MeV neutrons/cm 2 carried out May 8, 2005 in Ljubiana (Slovenia). Fluences: 1  10 14 n/cm 2, 3  10 14 n/cm 2, 7  10 14 n/cm 2, 1.5  10 15 n/cm 2, 3  10 15 n/cm 2, 1  10 16 n/cm 2.

9. 7 th RD50 Workshop CERN Geneva November 14-16 2005 Università degli Studi Università degli Studi di Perugia di Perugia 9 I-V on irradiated diodes Fluence 3  10 14 n/cm 2 Diameter = 1 mmAnnealing 7 days at RT

10. 7 th RD50 Workshop CERN Geneva November 14-16 2005 Università degli Studi Università degli Studi di Perugia di Perugia 10 I- V after irradiation Reverse current density decreases after irradiation! Diameter = 1 mm

11. 7 th RD50 Workshop CERN Geneva November 14-16 2005 Università degli Studi Università degli Studi di Perugia di Perugia 11 C-V after irradiation Capacitance is constant. The material turns to intrinsic Diameter = 0.4 mm

12. 7 th RD50 Workshop CERN Geneva November 14-16 2005 Università degli Studi Università degli Studi di Perugia di Perugia 12 CC measurements on irradiated diodes: analysis of data

13. 7 th RD50 Workshop CERN Geneva November 14-16 2005 Università degli Studi Università degli Studi di Perugia di Perugia 13 CC after irradiation Asymptotic value: 2800 e - after 1x10 14 n/cm 2. CCE 90% Asymptotic value: 800 e - after 1.5x10 15 n/cm 2. CCE 26% Detectors continue to operate Diameter = 1 mm

14. 7 th RD50 Workshop CERN Geneva November 14-16 2005 Università degli Studi Università degli Studi di Perugia di Perugia 14 CC vs fluence Diameter = 1 mm CC is high until some 10 14 n/cm 2 CC decreases sharply after 10 15 n/cm 2. Only 130 e - after 10 16 n/cm 2 Presently SiC is not radiation hard as we thought of!

15. 7 th RD50 Workshop CERN Geneva November 14-16 2005 Università degli Studi Università degli Studi di Perugia di Perugia 15 Conclusions p + n junctions have been made and electrically characterized. Good characteristics have been obtained CC experimental results on unirradiated SiC p + n junctions: 3000 e - are collected at 200 V Currents @ 500 V are very low even after fluences of the order of 10 16 n/cm 2. CC is good until fluences of the order of some 10 14 n/cm 2. Before annealing, for fluences of the order of 10 15 -10 16 n/cm 2 the CC is very low. Presently SiC is not radiation hard as we were thinking of

16. 7 th RD50 Workshop CERN Geneva November 14-16 2005 Università degli Studi Università degli Studi di Perugia di Perugia 16 Future developments Identification of the defects introduced by neutrons. Verification of the possibility to neutralize these defects. Annealing studies in order to verify the possibility to recover the radiation damage.