Progress on Charge Distribution in Multiply-Stacked Si Quantum Dots/SiO<SUB>2</SUB> Structure as Evaluated by AFM/KFM

Katsunori MAKIHARA; Mitsuhisa IKEDA; Seiichiro HIGASHI; Seiichi MIYAZAKI

doi:10.1093/ietele/e91-c.5.712

Progress on Charge Distribution in Multiply-Stacked Si Quantum Dots/SiO₂ Structure as Evaluated by AFM/KFM

Katsunori MAKIHARA, Mitsuhisa IKEDA, Seiichiro HIGASHI, Seiichi MIYAZAKI

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Multiply-stacked structures of Si quantum dots (Si-QDs) in gate oxide are attracting much attention because of their potential importance to improve retention characteristics in a high density charge storage. In this work, we have fabricated 6-fold stacked Si-QDs with 2 nm-thick SiO₂ interlayers, whose areal dot density and average dot size were 5.710¹¹ cm^-2 in each dot layer and 5 nm in height, and studied progress on electron distribution in 6-fold stacked Si-QDs with 2 nm-thick SiO₂ interlayers from the measurements of temporal changes in the surface potential after electron charging and discharging locally at room temperature using an AFM/Kelvin probe technique in clean room air. First, by scanning an area of 22 µm² with the AFM tip biased at +3 V with respect to the substrate in a tapping mode, the area was negatively charged due to electron injection from the substrate to the dot through the bottom tunnel oxide and subsequently, the central part of 100100 nm² in the pre-charged area was scanned with the tip biased at -3 V to emit the electrons from the Si-QDs to the substrate. As a result, the negative charging level was markedly reduced in the central part in comparison to its peripheral region. And then, the surface potential of the negatively-charged peripheral region was decay monotonously with time as a result of progressive electron tunneling to the substrate. In contrast to this, the temporal change in the surface potential of the central part shows that the electron charging proceeds with time until the surface potential becomes almost the same as that in the peripheral region. This result can be interpreted in terms of lateral spreading of electrons stored in the Si-QDs layer due to the potential difference between the central part and its peripheral region more negatively charged.

Publication: IEICE TRANSACTIONS on Electronics Vol.E91-C No.5 pp.712-715

Publication Date: 2008/05/01

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Online ISSN: 1745-1353

DOI: 10.1093/ietele/e91-c.5.712

Type of Manuscript: Special Section PAPER (Special Section on Fundamentals and Applications of Advanced Semiconductor Devices)

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Katsunori MAKIHARA, Mitsuhisa IKEDA, Seiichiro HIGASHI, Seiichi MIYAZAKI, "Progress on Charge Distribution in Multiply-Stacked Si Quantum Dots/SiO2 Structure as Evaluated by AFM/KFM" in IEICE TRANSACTIONS on Electronics, vol. E91-C, no. 5, pp. 712-715, May 2008, doi: 10.1093/ietele/e91-c.5.712.
Abstract: Multiply-stacked structures of Si quantum dots (Si-QDs) in gate oxide are attracting much attention because of their potential importance to improve retention characteristics in a high density charge storage. In this work, we have fabricated 6-fold stacked Si-QDs with 2 nm-thick SiO₂ interlayers, whose areal dot density and average dot size were 5.710¹¹ cm^-2 in each dot layer and 5 nm in height, and studied progress on electron distribution in 6-fold stacked Si-QDs with 2 nm-thick SiO₂ interlayers from the measurements of temporal changes in the surface potential after electron charging and discharging locally at room temperature using an AFM/Kelvin probe technique in clean room air. First, by scanning an area of 22 µm² with the AFM tip biased at +3 V with respect to the substrate in a tapping mode, the area was negatively charged due to electron injection from the substrate to the dot through the bottom tunnel oxide and subsequently, the central part of 100100 nm² in the pre-charged area was scanned with the tip biased at -3 V to emit the electrons from the Si-QDs to the substrate. As a result, the negative charging level was markedly reduced in the central part in comparison to its peripheral region. And then, the surface potential of the negatively-charged peripheral region was decay monotonously with time as a result of progressive electron tunneling to the substrate. In contrast to this, the temporal change in the surface potential of the central part shows that the electron charging proceeds with time until the surface potential becomes almost the same as that in the peripheral region. This result can be interpreted in terms of lateral spreading of electrons stored in the Si-QDs layer due to the potential difference between the central part and its peripheral region more negatively charged.
URL: https://global.ieice.org/en_transactions/electronics/10.1093/ietele/e91-c.5.712/_p

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@ARTICLE{e91-c_5_712,
author={Katsunori MAKIHARA, Mitsuhisa IKEDA, Seiichiro HIGASHI, Seiichi MIYAZAKI, },
journal={IEICE TRANSACTIONS on Electronics},
title={Progress on Charge Distribution in Multiply-Stacked Si Quantum Dots/SiO2 Structure as Evaluated by AFM/KFM},
year={2008},
volume={E91-C},
number={5},
pages={712-715},
abstract={Multiply-stacked structures of Si quantum dots (Si-QDs) in gate oxide are attracting much attention because of their potential importance to improve retention characteristics in a high density charge storage. In this work, we have fabricated 6-fold stacked Si-QDs with 2 nm-thick SiO₂ interlayers, whose areal dot density and average dot size were 5.710¹¹ cm^-2 in each dot layer and 5 nm in height, and studied progress on electron distribution in 6-fold stacked Si-QDs with 2 nm-thick SiO₂ interlayers from the measurements of temporal changes in the surface potential after electron charging and discharging locally at room temperature using an AFM/Kelvin probe technique in clean room air. First, by scanning an area of 22 µm² with the AFM tip biased at +3 V with respect to the substrate in a tapping mode, the area was negatively charged due to electron injection from the substrate to the dot through the bottom tunnel oxide and subsequently, the central part of 100100 nm² in the pre-charged area was scanned with the tip biased at -3 V to emit the electrons from the Si-QDs to the substrate. As a result, the negative charging level was markedly reduced in the central part in comparison to its peripheral region. And then, the surface potential of the negatively-charged peripheral region was decay monotonously with time as a result of progressive electron tunneling to the substrate. In contrast to this, the temporal change in the surface potential of the central part shows that the electron charging proceeds with time until the surface potential becomes almost the same as that in the peripheral region. This result can be interpreted in terms of lateral spreading of electrons stored in the Si-QDs layer due to the potential difference between the central part and its peripheral region more negatively charged.},
keywords={},
doi={10.1093/ietele/e91-c.5.712},
ISSN={1745-1353},
month={May},}

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TY - JOUR
TI - Progress on Charge Distribution in Multiply-Stacked Si Quantum Dots/SiO2 Structure as Evaluated by AFM/KFM
T2 - IEICE TRANSACTIONS on Electronics
SP - 712
EP - 715
AU - Katsunori MAKIHARA
AU - Mitsuhisa IKEDA
AU - Seiichiro HIGASHI
AU - Seiichi MIYAZAKI
PY - 2008
DO - 10.1093/ietele/e91-c.5.712
JO - IEICE TRANSACTIONS on Electronics
SN - 1745-1353
VL - E91-C
IS - 5
JA - IEICE TRANSACTIONS on Electronics
Y1 - May 2008
AB - Multiply-stacked structures of Si quantum dots (Si-QDs) in gate oxide are attracting much attention because of their potential importance to improve retention characteristics in a high density charge storage. In this work, we have fabricated 6-fold stacked Si-QDs with 2 nm-thick SiO₂ interlayers, whose areal dot density and average dot size were 5.710¹¹ cm^-2 in each dot layer and 5 nm in height, and studied progress on electron distribution in 6-fold stacked Si-QDs with 2 nm-thick SiO₂ interlayers from the measurements of temporal changes in the surface potential after electron charging and discharging locally at room temperature using an AFM/Kelvin probe technique in clean room air. First, by scanning an area of 22 µm² with the AFM tip biased at +3 V with respect to the substrate in a tapping mode, the area was negatively charged due to electron injection from the substrate to the dot through the bottom tunnel oxide and subsequently, the central part of 100100 nm² in the pre-charged area was scanned with the tip biased at -3 V to emit the electrons from the Si-QDs to the substrate. As a result, the negative charging level was markedly reduced in the central part in comparison to its peripheral region. And then, the surface potential of the negatively-charged peripheral region was decay monotonously with time as a result of progressive electron tunneling to the substrate. In contrast to this, the temporal change in the surface potential of the central part shows that the electron charging proceeds with time until the surface potential becomes almost the same as that in the peripheral region. This result can be interpreted in terms of lateral spreading of electrons stored in the Si-QDs layer due to the potential difference between the central part and its peripheral region more negatively charged.
ER -