Experience with CiS detectors at NIKHEF Fred Hartjes, Sandra Muijs, uExperience from lFive-module miniproduction of spring 2002 lTwo prequalifier modules February 2003 lLatest CiS batch 5195 uImprovement by burn-in uConclusions Meeting on CiS reception tests, 16 April 2003

Fred Hartjes, Sandra Muijs 2 Meeting on CiS reception tests 16 April 2003 CERN Introduction

Fred Hartjes, Sandra Muijs 3 Meeting on CiS reception tests 16 April 2003 CERN IV characteristics uExample: Module 15 (CiS batch 5194) uMPI curve shows breakdown starting at 250 V uFor NIKHEF curve breakdown starts at 400 V uGeneral tendencies of batch 4893 and 5194 lBreakdown starting at 400 V lBreakdown disappearing after assembly and wire bonding uAll modules can held 450 V

Fred Hartjes, Sandra Muijs 4 Meeting on CiS reception tests 16 April 2003 CERN IV curve for module 16 uBatch 5194 uAgain early breakdown observed by MPI, not seen by NIKHEF uAgain breakdown above 400 V disappearing after assembly and wire bonding

Fred Hartjes, Sandra Muijs 5 Meeting on CiS reception tests 16 April 2003 CERN IV curve for module 14 uBatch 5194 uNo MPI data for detector 01, value of 10 is doubled uAgain breakdown above 400 V disappearing after assembly and wire bonding

Fred Hartjes, Sandra Muijs 6 Meeting on CiS reception tests 16 April 2003 CERN IV curve for module 13 uBatch 4893 lNo curve from on database uBreakdown at low bias current, no breakdown at high bias current

Fred Hartjes, Sandra Muijs 7 Meeting on CiS reception tests 16 April 2003 CERN IV curve for module 12 uBatch 4893 lNo curve from on database uInitial current extremely low, back to normal level after wire bonding

Fred Hartjes, Sandra Muijs 8 Meeting on CiS reception tests 16 April 2003 CERN IV curves of all 5 modules AFTER wirebonding uCurves almost alike u(almost) no sign of breakdown

Fred Hartjes, Sandra Muijs 9 Meeting on CiS reception tests 16 April 2003 CERN IV curves module 511 IV curves at different stages during the assembly: In blue, the sum of the IV curves of the individual wafers (reception tests) In orange, the corresponding measurements made by CiS In green, the sum of the front and back wafer after they have been glued to the spine In red, the IV curve of the module, after bonding The breakdown behaviour of the unbonded glued wafers is observed before in earlier modules made at NIKHEF. It appears to be typical behaviour for CiS wafers: as long as they are unbonded, the behaviour is rather unpredictable.

Fred Hartjes, Sandra Muijs 10 Meeting on CiS reception tests 16 April 2003 CERN IV curves module K5-512 IV curves at different stages during the assembly: In blue, the sum of the IV curves of the individual wafers (reception tests) In orange, the corresponding measurements made by CiS In green, the sum of the front and back wafer after they have been glued to the spine In red, the IV curve of the module, after bonding The breakdown did not disappear after bonding, so these wafers were indeed not good enough to build modules (NB they were selected for dummy modules only).

Fred Hartjes, Sandra Muijs 11 Meeting on CiS reception tests 16 April 2003 CERN Training of sensor by successive IV measurements uBreakdown voltage gets higher after each measurement uLow I bias at 100 V => low V breakdown uHigh I bias at 100 V => high V breakdown

Fred Hartjes, Sandra Muijs 12 Meeting on CiS reception tests 16 April 2003 CERN Burning-in sensors uBatch 5195 lStable after 80 min uBatch 5005 lStable after 5 min

Fred Hartjes, Sandra Muijs 13 Meeting on CiS reception tests 16 April 2003 CERN Sensor after burn-in uMeasured a few minutes after burn-in uAlmost flat after depletion uI bias about 100 nA higher than before burn-in uNo sign of breakdown until 500 V! uStarting at negative I bias uAbsolutely no hysteresis above 180 V

Fred Hartjes, Sandra Muijs 14 Meeting on CiS reception tests 16 April 2003 CERN Sensor before and after burn-in uImprovement less striking than for batch 5195 uMinor breakdown starting at 470 V

Fred Hartjes, Sandra Muijs 15 Meeting on CiS reception tests 16 April 2003 CERN Conclusions uSensor properties strongly differing between different batches uNot possible to verify the correct sensor handling during module assembly (experience of five-module miniproduction) uEarly breakdown often accompanied by low bias current uGrounding strips makes IV curves of two different batches almost equal