Study of Er-related defects in a-Si:H(Er) films used in light emitting heterostructures

A. Nazarov, Ja Vovk, V. Lysenko, O. Kon'kov, E. Terukov, S. Ashok

Research output: Contribution to journalConference articlepeer-review

Abstract

Defects relating to Er-doping of hydrogenated amorphous silicon films in amorphous/ crystalline (a-Si:H(Er) / n-Si) heterostructures used as light emitters were studied. Electrical parameters of the defects were evaluated by thermally activated current (TAC) and capacitance (TACap) spectroscopy, and high-frequency (1 MHz) capacitance-voltage (C-V) characteristics measured at 77 K. For charging of the traps, visible light illumination at low temperatures and thermal-bias stress at various temperatures were used. The amplitude of TAC was found to increase monotonically with increase of Er concentration in the a-Si:H film. The traps, with activation energies in the range 0.10 - 0.35 eV and 0.5 - 0.6 eV, were charged under both light and thermal-bias stress, and may be associated with the deep levels in the band-gap of a-Si:H. High-temperature current peaks with activation energies of 0.8-0.9 eV emerged only under thermal-bias stress and were strongly dependent on the charging temperature. It is suggested that these high-temperature thermally activated processes are related to polarization of the Er-O bonds in the amorphous matrix of a-Si:H. C-V measurements show that charging of the structure by negative substrate bias leads to net electron trapping in the a-Si:H(Er) film, whereas charging by positive bias result in net hole trapping. The model of Er-related electroluminescence in a-Si:H(Er) / n-Si heterostructures involving electron-hole recombination via deep levels located in the vicinity of [Er-O] inclusions is discussed.

Original languageEnglish (US)
Pages (from-to)145-150
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Volume719
DOIs
StatePublished - 2002
EventDefect and Impunity Engineered Semiconductors and Devices III - San Francisco, CA, United States
Duration: Apr 1 2002Apr 5 2002

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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