The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Development of Radiation Hard Radiation Detectors – Differences Between Czochralski Silicon and Float Zone Silicon

Eija Tuominen

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Electrical and Communications Engineering for public examination and debate in Auditorium S4 at Helsinki University of Technology (Espoo, Finland) on the 10th of October, 2003, at 12 o'clock noon.

Overview in PDF format (ISBN 951-22-6741-1)   [1249 KB]
Dissertation is also available in print (ISBN 952-10-1264-1)

Abstract

The purpose of this work was to develop radiation hard silicon detectors. Radiation detectors made of silicon are cost effective and have excellent position resolution. Therefore, they are widely used for track finding and particle analysis in large high-energy physics experiments. Silicon detectors will also be used in the CMS (Compact Muon Solenoid) experiment that is being built at the LHC (Large Hadron Collider) accelerator at CERN (European Organisation for Nuclear Research). This work was done in the CMS programme of Helsinki Institute of Physics (HIP).

Exposure of the silicon material to particle radiation causes irreversible defects that deteriorate the performance of the silicon detectors. In HIP CMS Programme, our approach was to improve the radiation hardness of the silicon material with increased oxygen concentration in silicon material. We studied two different methods: diffusion oxygenation of Float Zone silicon and use of high resistivity Czochralski silicon.

We processed, characterised, tested in a particle beam, and irradiated silicon detectors and test structures. Samples were processed at the clean room facilities of Helsinki University of Technology Microelectronics Centre (MEC) where our group has the status of a member laboratory. Electrical characterisations were done mainly at CERN at the premises of our collaborators from CERN RD39 and RD50 research and development programmes, where our group is participating as a member institute. Defect characterisations were carried out using PCD (Photoconductivity Decay) and SPV (Surface Photovoltage) methods at Helsinki University of Technology Electron Physics Laboratory. Detection performance was measured with a Helsinki Silicon Beam telescope at CERN using muon beam. Radiation hardness was studied in irradiation tests at Jyväskylä University Accelerator Laboratory.

Our research on the radiation hardness of diffusion oxygenated Float Zone silicon resulted in several previously unreported findings. We found an evident correlation between silicon oxygenation and detector leakage current after irradiations. Additionally, we found that the oxygenation has a positive effect on the long-term stability of irradiated silicon. Furthermore, we successfully applied alternative methods for the characterisation of silicon detectors, i.e. PCD (Photoconductivity Decay) and SPV (Surface Photovoltage).

The most important results of our research were obtained in our work on high resistivity Czochralski silicon. Although the advantages of Czochralski silicon had been known for some time, we were the first group to process, characterise, test in a particle beam, and irradiate full-size Czochralski silicon detectors. In proton irradiations, Czochralski silicon was found to be more radiation hard than any other silicon material.

This thesis consists of an overview and of the following 7 publications:

  1. Härkönen J., Tuominen E., Lassila-Perini K., Palokangas M., Yli-Koski M., Heikkilä P., Ovchinnikov V., Palmu L. and Kallijärvi S., 2002. Processing and recombination lifetime characterization of silicon microstrip detectors. Nuclear Instruments and Methods in Physics Research A 485, pages 159-165.
  2. Härkönen J., Tuominen E., Tuovinen E., Lassila-Perini K., Nummela S., Nysten J., Heikkilä P., Ovchinnikov V., Palokangas M., Yli-Koski M., Palmu L., Kallijärvi S., Alanko T., Laitinen P., Pirojenko A., Riihimäki I., Tiourine G. and Virtanen A., 2002. The effect of oxygenation on the radiation hardness of silicon studied by surface photovoltage method. IEEE Transactions on Nuclear Science 49, No. 6, pages 2910-2913.
  3. Härkönen J., Tuominen E., Tuovinen E., Lassila-Perini K., Nummela S., Nysten J., Heikkilä P., Ovchinnikov V., Palokangas M., Yli-Koski M., Palmu L., Kallijärvi S., Alanko T., Laitinen P., Pirojenko A., Riihimäki I., Tiourine G. and Virtanen A., Annealing study of oxygenated and non-oxygenated Float Zone silicon irradiated with 15 MeV protons. Nuclear Instruments and Methods in Physics Research A, in press.
  4. Härkönen J., Tuominen E., Tuovinen E., Heikkilä P., Ovchinnikov V., Yli-Koski M., Palmu L., Kallijärvi S., Nikkilä H. and Anttila O., Processing of microstrip detectors on Czochralski grown high resistivity silicon substrates. Nuclear Instruments and Methods in Physics Research A, in press.
  5. Tuominen E., Banzuzi K., Czellar S., Heikkinen A., Härkönen J., Johansson P., Karimäki V., Luukka P., Mehtälä P., Niku J., Nummela S., Nysten J., Simpura J., Tuovinen E., Tuominiemi J., Ungaro D., Vaarala T., Wendland L., Voutilainen M. and Zibellini A., 2003. Test beam results of a large area strip detector made on high resistivity Czochralski silicon. Nuclear Physics B (Proceedings Supplements) 125 C, pages 175-178.
  6. Tuominen E., Härkönen J., Tuovinen E., Lassila-Perini K., Luukka P., Mehtälä P., Nummela S., Nysten J., Zibellini A., Li Z., Heikkilä P., Ovchinnikov V., Yli-Koski M., Laitinen P., Riihimäki I. and Virtanen A., 2003. Radiation hardness of Czochralski silicon studied by 10 MeV and 20 MeV protons. IEEE Transactions on Nuclear Science, submitted for publication. Currently available: Helsinki Institute of Physics, Preprint series, HIP-2003-17/EXP, 4 pages.
  7. Banzuzi K., Czellar S., Heikkinen A., Härkönen J., Karimäki V., Leppänen M., Luukka P., Nummela S., Pietarinen E., Tuominen E., Tuominiemi J. and Wendland L., 2001. Test beam results with upgraded Helsinki Silicon Beam Telescope. Helsinki Institute of Physics, Internal report, HIP-2001-08, 27 pages.

Keywords: silicon detectors, radiation detectors, resistivity, radiation hardness, oxygenation, development, Photoconductive Decay, Surface Photovoltage, Deep Level Transient Spectroscopy

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© 2003 Helsinki University of Technology

Last update 2011-05-26