Imaging of oxide charges and contact potential difference fluctuations in Atomic Layer Deposited Al2O3 on Si

Research output: Contribution to journalArticleAcademicpeer-review

13 Citations (Scopus)

Abstract

Ultrathin 2.5 nm high-k aluminum oxide (Al2O3) films on p-type silicon (001) deposited by atomic layer deposition (ALD) were investigated with noncontact atomic force microscopy (NC-AFM) in ultrahigh vacuum, using a conductive tip. Constant force gradient images revealed the presence of oxide charges and experimental observations at different tip-sample potentials were compared with calculations of the electric force gradient based on a spherical tip model. This model could be substantially improved by the incorporation of the image of the tip in the semiconductor substrate. Based on the signals of different oxide charges observed, a homogenous depth distribution of those charges was derived. Application of a potential difference between sample and tip was found to result in a net electric force depending on the contact potential difference (CPD) and effective tip-sample capacitance, which depends on the depletion or accumulation layer that is induced by the bias voltage. CPD images could be constructed from height-voltage spectra with active feedback. Apart from oxide charges large-scale (150-300 nm lateral size) and small-scale (50-100 nm) CPD fluctuations were observed, the latter showing a high degree of correlation with topography features. This correlation might be a result from the surface-inhibited growth mode of the investigated layers.
Original languageUndefined
Article number10.1063/1.1870113
Pages (from-to)063709
Number of pages8
JournalJournal of applied physics
Volume97
Issue number063709
DOIs
Publication statusPublished - 14 Mar 2005

Keywords

  • IR-67703
  • EWI-15497
  • METIS-224038

Cite this

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title = "Imaging of oxide charges and contact potential difference fluctuations in Atomic Layer Deposited Al2O3 on Si",
abstract = "Ultrathin 2.5 nm high-k aluminum oxide (Al2O3) films on p-type silicon (001) deposited by atomic layer deposition (ALD) were investigated with noncontact atomic force microscopy (NC-AFM) in ultrahigh vacuum, using a conductive tip. Constant force gradient images revealed the presence of oxide charges and experimental observations at different tip-sample potentials were compared with calculations of the electric force gradient based on a spherical tip model. This model could be substantially improved by the incorporation of the image of the tip in the semiconductor substrate. Based on the signals of different oxide charges observed, a homogenous depth distribution of those charges was derived. Application of a potential difference between sample and tip was found to result in a net electric force depending on the contact potential difference (CPD) and effective tip-sample capacitance, which depends on the depletion or accumulation layer that is induced by the bias voltage. CPD images could be constructed from height-voltage spectra with active feedback. Apart from oxide charges large-scale (150-300 nm lateral size) and small-scale (50-100 nm) CPD fluctuations were observed, the latter showing a high degree of correlation with topography features. This correlation might be a result from the surface-inhibited growth mode of the investigated layers.",
keywords = "IR-67703, EWI-15497, METIS-224038",
author = "Sturm, {Jacobus Marinus} and A. Zinine and Herbert Wormeester and Bene Poelsema and R.G. Bankras and J. Holleman and Jurriaan Schmitz",
year = "2005",
month = "3",
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doi = "10.1063/1.1870113",
language = "Undefined",
volume = "97",
pages = "063709",
journal = "Journal of applied physics",
issn = "0021-8979",
publisher = "American Institute of Physics",
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Imaging of oxide charges and contact potential difference fluctuations in Atomic Layer Deposited Al2O3 on Si. / Sturm, Jacobus Marinus; Zinine, A.; Wormeester, Herbert; Poelsema, Bene; Bankras, R.G.; Holleman, J.; Schmitz, Jurriaan.

In: Journal of applied physics, Vol. 97, No. 063709, 10.1063/1.1870113, 14.03.2005, p. 063709.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Imaging of oxide charges and contact potential difference fluctuations in Atomic Layer Deposited Al2O3 on Si

AU - Sturm, Jacobus Marinus

AU - Zinine, A.

AU - Wormeester, Herbert

AU - Poelsema, Bene

AU - Bankras, R.G.

AU - Holleman, J.

AU - Schmitz, Jurriaan

PY - 2005/3/14

Y1 - 2005/3/14

N2 - Ultrathin 2.5 nm high-k aluminum oxide (Al2O3) films on p-type silicon (001) deposited by atomic layer deposition (ALD) were investigated with noncontact atomic force microscopy (NC-AFM) in ultrahigh vacuum, using a conductive tip. Constant force gradient images revealed the presence of oxide charges and experimental observations at different tip-sample potentials were compared with calculations of the electric force gradient based on a spherical tip model. This model could be substantially improved by the incorporation of the image of the tip in the semiconductor substrate. Based on the signals of different oxide charges observed, a homogenous depth distribution of those charges was derived. Application of a potential difference between sample and tip was found to result in a net electric force depending on the contact potential difference (CPD) and effective tip-sample capacitance, which depends on the depletion or accumulation layer that is induced by the bias voltage. CPD images could be constructed from height-voltage spectra with active feedback. Apart from oxide charges large-scale (150-300 nm lateral size) and small-scale (50-100 nm) CPD fluctuations were observed, the latter showing a high degree of correlation with topography features. This correlation might be a result from the surface-inhibited growth mode of the investigated layers.

AB - Ultrathin 2.5 nm high-k aluminum oxide (Al2O3) films on p-type silicon (001) deposited by atomic layer deposition (ALD) were investigated with noncontact atomic force microscopy (NC-AFM) in ultrahigh vacuum, using a conductive tip. Constant force gradient images revealed the presence of oxide charges and experimental observations at different tip-sample potentials were compared with calculations of the electric force gradient based on a spherical tip model. This model could be substantially improved by the incorporation of the image of the tip in the semiconductor substrate. Based on the signals of different oxide charges observed, a homogenous depth distribution of those charges was derived. Application of a potential difference between sample and tip was found to result in a net electric force depending on the contact potential difference (CPD) and effective tip-sample capacitance, which depends on the depletion or accumulation layer that is induced by the bias voltage. CPD images could be constructed from height-voltage spectra with active feedback. Apart from oxide charges large-scale (150-300 nm lateral size) and small-scale (50-100 nm) CPD fluctuations were observed, the latter showing a high degree of correlation with topography features. This correlation might be a result from the surface-inhibited growth mode of the investigated layers.

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KW - METIS-224038

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