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The WODEAN project – outline and present status

The WODEAN project – outline and present status. Gunnar Lindstroem – Hamburg University for the WODEAN collaboration. How it all began Methods-Institutes-Persons Outline of correlated project Present status Preliminary results Outlook.

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The WODEAN project – outline and present status

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  1. The WODEAN project – outline and present status Gunnar Lindstroem – Hamburg Universityfor the WODEAN collaboration • How it all began • Methods-Institutes-Persons • Outline of correlated project • Present status • Preliminary results • Outlook 10th RD50 workshop - Vilnius University 04/06-June-07

  2. WODEAN (WOrkshop on DEfect ANalysis), 1st meeting in Hamburg, 23-25 August 2006idea triggered by Gordon Davies‘ talk at RD50, CERN, Nov. 2005we need all available tools (not only DLTS, TSC)for thorough defect analysis and possible defect engineering 10th RD50 workshop - Vilnius University 04/06-June-07

  3. Methods-Institutes-Persons C-DLTS:NIMP Bucharest and Hamburg University: I. Pintilie, E. Fretwurst, G. LindstroemMinsk University: L. MakarenkoOslo University: B. SvenssonI-DLTS:INFN and Florence University: D. MenichelliTSC:NIMPBucharest and Hamburg University: I. Pintilie, E. Fretwurst, G. LindstroemPITS:ITME Warsaw: P. Kaminski, R. KozlowskiPL:Kings College London: G. DaviesITME Warsaw: B. SurmaRecombination lifetime:Vilnius University: E. Gaubas, J. VaitkusFTIR:Oslo University and Minsk Joint Institute of Solid State and Semicond. Pysics: L. Murin, B. SvenssonPC:Vilnius University:J. Vaitkus, E. GaubasEPR:NIMP Bucharest: S. NistorITME Warsaw: M. PawlowskiDiode characteristics (C/V, I/V, TCT):CERN-PH, Hamburg University, JSI Ljubljana: M. Moll, E. Fretwurst, G. Lindstroem, G. Kramberger AND VERY IMPORTAN TOO: Irraditions:JSI Ljubljana: G. Kramberger 10th RD50 workshop - Vilnius University 04/06-June-07

  4. Outline of Correlated Project • Main issue:Feq to be tolerated in S-LHC: 1.5E16 n/cm². charge trapping: ultimate limitation for detector applications responsible trapping source: so far unknown! • Charge trapping: independent of material type (FZ, CZ, epi) and properties (std, DO, resistivity, doping type). independent of irradiating particle type and energy (23 GeV protons, reactor neutrons), if F normalised to 1 MeV neutron equivalent values (NIEL). In contrast to IFD and Neff there are only small annealing effects (as studied up to T = 80°C) • Correlated project:use all available methods: DLTS, TSC, PITS, PL, trecomb, FTIR, PC, EPR, diode C/V, I/V and TCTconcentrate on single material only: MCz chosen with extension to std. FZ for checking of unexpected results (FZ supposed to be cleaner, MCz has larger O concentration) Use only one type of irradiation, most readily available (TRIGA reactor at Ljubljana) and do limited number of F steps between 3E11 and 3E16 n/cm²(same for all methods!)Use same isothermal annealing steps for all methodsReach first results within one year 10th RD50 workshop - Vilnius University 04/06-June-07

  5. 1st WODEAN batch sample list 150 samples n-MCz <100>1 kΩcm (OKMETIC, CiS):84 diodes, 48nude standard, 16 nude thick 10th RD50 workshop - Vilnius University 04/06-June-07

  6. 2nd WODEAN batch sample list 90 samples n-FZ <111>, 2 kΩcm (Wacker, STM):67 diodes, 24 nude thick samples; 10th RD50 workshop - Vilnius University 04/06-June-07

  7. Irradiations 1st batch, MCz samples:Irradiation: November 2006Delivery to Hamburg: 8 January 2007Distribution to WODEAN members: 9 February 2007 2nd batch, FZ samples:Irradiation: April 2007Delivery to Hamburg: 11 June (foreseen)Distribution to WODEAN members: end June 2007 Important Info about irradiations: F≤ 1E+15 n/cm²: T ≈ 20°C, duration ≤ 10 min F ≥ 2E+15 n/cm²: high flux: dF/dt = 2E12 n/cm²sTemperature increase during irradiation3E+15: t ≈ 25 min, temp. rising to 70-80°C within 15 min (then saturating) 1E+16:t ≈ 80 min, temp. 70-80°C as meas. with PT100 3E+16: t ≈ 4h, 10min, severe self annealing expected ? 10th RD50 workshop - Vilnius University 04/06-June-07

  8. Present Status • Macroscopic results • C/V and I/V diode characteristics Stable damage I/V = aF, a = 4.1E-17 A/cm As expected, no surprises for reverse annealing 10th RD50 workshop - Vilnius University 04/06-June-07

  9. Macroscopic results 2. TCT: trapping times, surprise in isochronal annealing! Isothermal annealing at 80°Cmax: 30% effect Isochronal anneal 80-260°Cstable h-trappinge-trapping reduced by factor 5 10th RD50 workshop - Vilnius University 04/06-June-07

  10. Microscopic results 1. DLTS isothermal anneal at 80°C and 200°C Annealing of vacancy cluster, increase of VO and signal for V2=/- 10th RD50 workshop - Vilnius University 04/06-June-07

  11. Measurements after 6 MeV electron irradiation: Difference between DLTS spectra Loss of VO, V2=/- and E5 vs loss of E4 E4 E5 E4 and E5 vacancy cluster related, 1:1 correlationliberation of V leads to increase of VO 10th RD50 workshop - Vilnius University 04/06-June-07

  12. 2. TSC isothermal anneal at 80°C Annealing of vacancy cluster, generation of H116K (reverse annealing related?) and increase of CiOi 10th RD50 workshop - Vilnius University 04/06-June-07

  13. 3. FTIR Fluence dependence Isothedrmal annealing of I2O Increase of defect concentration with fluence 1st order processactivation energy 1.16 eV 10th RD50 workshop - Vilnius University 04/06-June-07

  14. 4. PL Summary of annealing As received: low PL intensity, CiOi plus broad band At 80 C, no change in bandshapes after 4 mins. After 30 mins, start of observing weak CiCs and W; W continues to increase after 12 hrs and 24 hrs.After 450 C, ‘point defects’ to 1e14 cm-2; increasing dominance of broad band at higher fluences. 10th RD50 workshop - Vilnius University 04/06-June-07

  15. 5. Photo Induced Transient Spectroscopy- Example - 10th RD50 workshop - Vilnius University 04/06-June-07

  16. 6. Photo Conductivity - Spectra- Example - F = 1E13 n/cm² F = 1E15 n/cm² Deep traps 10th RD50 workshop - Vilnius University 04/06-June-07

  17. 7. Recombination lifetime - 1/t F, annealing improves lifetime 10th RD50 workshop - Vilnius University 04/06-June-07

  18. Outlook Most surprising result from TCT: isochronal annealing shows reduction of electron trapping Strong changes also observed after high temp. Steps inDLTS, TSC, PL and FTIR Consequence: start with 80°C annealing and then go in 40°C steps up to at least 240°C or even higher Search for close to midgap defects using lower resistivity material, epi most likely available! Exchange of results between members will be intensifiedas best going on continuously, next meeting: end this year! 10th RD50 workshop - Vilnius University 04/06-June-07

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