Processing of AC-coupled n-in-p pixel detectors on MCz silicon using atomic layer deposited aluminium oxide

Research output: Contribution to journalArticle


  • Jennifer Ott

  • A. Gädda
  • S. Bharthuar
  • E. Brücken
  • M. Golovleva
  • J. Härkönen
  • M. Kalliokoski
  • A. Karadzhinova-Ferrer
  • S. Kirschenmann
  • V. Litichevskyi
  • P. Luukka
  • L. Martikainen
  • T. Naaranoja

Research units

  • University of Helsinki
  • Lappeenranta University of Technology
  • Ruder Boskovic Institute
  • University of Helsinki
  • Advacam Ltd.


We report on the fabrication of capacitively (AC) coupled n+-in-p pixel detectors on magnetic Czochralski silicon substrates. In our devices, we employ a layer of aluminium oxide (Al2O3) grown by atomic layer deposition (ALD) as dielectric and field insulator, instead of the commonly used silicon dioxide (SiO2). As shown in earlier research, Al2O3 thin films exhibit high negative oxide charge, and can thus serve as a substitute for p-stop/p-spray insulation implants between pixels. In addition, they provide far higher capacitance densities than SiO2 due to their high dielectric constant, permitting more efficient capacitive coupling of pixels. Furthermore, metallic titanium nitride (TiN) bias resistors are presented as an alternative to punch-through or poly-Si resistors. Devices obtained by the above mentioned process are characterized by capacitance–voltage and current–voltage measurements, and by 2 MeV proton microprobe. Results show the expected high negative charge of the Al2O3 dielectric, uniform charge collection efficiency over large areas of pixels, and acceptable leakage current densities.


Original languageEnglish
Article number162547
JournalNuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Publication statusE-pub ahead of print - 1 Jan 2019
MoE publication typeA1 Journal article-refereed

    Research areas

  • AlO, Atomic layer deposition (ALD), Capacitive coupling, Pixel detector

ID: 36339006