Characterization of epiready n+-GaAs (100) surfaces by SPV-transient

Juha Sinkkonen (Corresponding author), Sergey Novikov, Aapo Varpula, J. Haapamaa

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

5 Citations (Scopus)

Abstract

Surface photovoltage (SPV) transient provides a non-destructive, contact-free method for characterization of semiconductor surfaces. Here we study SPV-transients of differently cleaned, heavily doped epiready GaAs wafers. After a rapid initial part the transient shows a very slow decay taking place in 100 - 1000 s time scale. Chemical NH4OH:H2O 2:H2O cleaning and atomic hydrogen UHV cleaning are applied. SPV-transients are measured by Kelvin probe in normal atmospheric conditions. A large signal surface trapping model is developed which includes both majority and minority carrier processes and covers the whole light on, steady state, light off sequence. Model fitting allows band bending, energy and density of surface states as well as electron and hole capture cross-sections to be extracted. The results show that the traps are electronic states in thin oxide layer covering the samples. This conclusion is based on the finding that the capture cross-sections are very small, in the range 10-19 - 10-26 cm2, which calls tunneling for explanation. This indicates that after cleaning the oxide layer is rapidly re-grown in laboratory atmosphere in less than 30 min. Typical band bendings are 0.6 - 0.8 eV, trap energies are slightly above the mid-gap and the density of occupied trap states is around 5×1012 cm-2 at thermal equilibrium.

Original languageEnglish
Title of host publicationProceedings of Spie - The International Society for Optical Engineering
Subtitle of host publicationDevice and Process Technologies for Microelectronics, MEMS, Photonics, and Nanotechnology IV
PublisherInternational Society for Optics and Photonics SPIE
Volume6800
ISBN (Print)978-081946971-7
DOIs
Publication statusPublished - 31 Mar 2008
MoE publication typeA4 Article in a conference publication
EventDevice and Process Technologies for Microelectronics, MEMS, Photonics, and Nanotechnology IV - Canberra, Australia
Duration: 5 Dec 20077 Dec 2007

Conference

ConferenceDevice and Process Technologies for Microelectronics, MEMS, Photonics, and Nanotechnology IV
CountryAustralia
CityCanberra
Period5/12/077/12/07

Keywords

  • Kelvin probe
  • Slow traps
  • Surface photovoltage transient
  • Tunneling assisted trapping

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    Sinkkonen, J., Novikov, S., Varpula, A., & Haapamaa, J. (2008). Characterization of epiready n+-GaAs (100) surfaces by SPV-transient. In Proceedings of Spie - The International Society for Optical Engineering: Device and Process Technologies for Microelectronics, MEMS, Photonics, and Nanotechnology IV (Vol. 6800). [68001D] International Society for Optics and Photonics SPIE. https://doi.org/10.1117/12.759378