Passivation of HPGe Detectors at LNL-INFN Speaker: Gianluigi Maggioni Materials & Detectors Laboratory (LNL-INFN) Scientific Manager: Prof. Gianantonio Della Mea Staff 2 Ph.D. in Materials Engineering 1 Ph.D. in Chemistry 1 Degree in Materials Science 3 Engineers (in Electronics and Materials Science) 1 Technician 3 Ph.D. Students in Physics, Materials Science and Engineering The activities of the Lab are devoted to the: 1.Synthesis of new materials (thin and thick films) 2.Modification of materials 3.Characterization of the physical / chemical properties of materials The research activities are mainly funded by INFN (about 3 experiments per year starting from nineties in the framework of V INFN Commitee) by inter-University MIUR research programs, by other National and International Research Institutions.

1. Synthesis of Materials PVD Facilities  6 Sputtering deposition apparatuses  2 High Vacuum Evaporation chambers  1 Glow-Discharge-induced Sublimation apparatus Chemical Techniques  Spin Coating  Sol-Gel  Tape Casting  Solvent Casting  Liquid Phase Deposition

2. Modification of Materials  Ion implantation  Heat Treatments in High Vacuum or in controlled atmospheres (2 furnaces up to 1600°C and 1200°C, respectively)  Ion Exchange, which allows to diffuse metal ions (Cu, Ag, Au,..) into the surface of glass and polymer materials  Surface chemical treatments (controlled etching)  UV treatment chamber  Climatic chamber at controlled temperature and humidity

3. Characterization of the physical / chemical properties of materials  Composition (Nuclear Techniques: RBS, ERDA, NRA, IBIL, PIXE)  Morphology (AFM, SEM)  Electrical Properties (resistivity, surface resistance, dielectric breakdown field)  Mechanical Properties (Micro Scratch Test, Nano Indentation, Micro Indentation)  Chemical Structure (FT-IR Analysis)  Optical Properties (UV-visible spectrophotometry)

Previous experience in Germanium Detectors Technology Collaboration project with EG&G Ortec “Advanced passivating techniques for the development of ruggedized HPGe detectors” ( ) Aim: an alternative to the detector encapsulation procedure (complex, expensive,...) Passivation techniques: deposition of oxides layers by liquid phase deposition (LPD) These techniques were not adopted because they could not be easily applied to industrial production (according to EG&G Ortec)

New passivation technique: Vacuum Deposition of a Polymer Layer

Polymer Deposition Apparatus New passivation technique: Vacuum Deposition of a Polymer Layer

Polymer Deposition Apparatus New passivation technique: Vacuum Deposition of a Polymer Layer HPGe Detector

New passivation technique: Vacuum Deposition of a Polymer Layer Vacuum Deposition Process (no solvent) Room Temperature Deposition Process Post-deposition curing is not required Very clean deposition process (compatibility with clean room operations) Detectors with complex shape can be coated Very low permeability to moisture, oxygen, … (barrier properties) Electrically insulating material (  > Ohm cm) High thermal resistance (Tg °C) The coated detector can be handled Layer thickness: 1 to 50  m Radiation hardness

1. Synthesis of Materials: PVD Facilities JOULE-EFFECT EVAPORATION 2 High Vacuum Evaporation systems:  Co-deposition of various elements or compounds  Synthesis of organic films and polymer films (polyimides) starting from co-deposition of monomers (Vapour Deposition Polymerization) followed by vacuum annealing (T  °C)

1. Synthesis of Materials: PVD Facilities GLOW DISCHARGE induced SUBLIMATION (GDS) 1 system for the deposition of organic and polymeric films  Deposition of organic and metal-organic films  Deposition of polymer films (polyimide) starting from the precursor monomer powders (Glow Discharge induced Vapour Deposition Polymerization)  Deposition of metal-containing polymer films by co-deposition of metal (sputtering) and polymer (GDVDP)  Quartz crystal microbalances  Ion mass and energy analyser for plasma diagnostics (mass range: 1 to 510 amu; energy range: ±100 eV)  Optical emission spectroscopy (optical range: 250 to 850 nm)  Rotating and biasable sample holders  High vacuum chamber: base pressure ≈ 5x10 -7 mbar  2 cathodes (1” and 2” diameter) RF-driven (600 W, MHz)  DC biasable sample-holder  2 Quartz micro-balances  Ion mass and energy analyser for the measurement gas-phase organic molecules  Optical emission spectrometer

Polymer 1Polymer 2Polymer 3

 Radiation Hardness