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Atom devices based on single dopants in silicon nanostructures.

Moraru D, Udhiarto A, Anwar M, Nowak R, Jablonski R, Hamid E, Tarido JC, Mizuno T, Tabe M - Nanoscale Res Lett (2011)

Bottom Line: Such technological trend brought us to a research stage on devices working with one or a few dopant atoms.In this work, we review our most recent studies on key atom devices with fundamental structures of silicon-on-insulator MOSFETs, such as single-dopant transistors, preliminary memory devices, single-electron turnstile devices and photonic devices, in which electron tunneling mediated by single dopant atoms is the essential transport mechanism.These results may pave the way for the development of a new device technology, i.e., single-dopant atom electronics.

View Article: PubMed Central - HTML - PubMed

Affiliation: Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Nakaku, Hamamatsu, 432-8011, Japan. romtabe@rie.shizuoka.ac.jp.

ABSTRACT
Silicon field-effect transistors have now reached gate lengths of only a few tens of nanometers, containing a countable number of dopants in the channel. Such technological trend brought us to a research stage on devices working with one or a few dopant atoms. In this work, we review our most recent studies on key atom devices with fundamental structures of silicon-on-insulator MOSFETs, such as single-dopant transistors, preliminary memory devices, single-electron turnstile devices and photonic devices, in which electron tunneling mediated by single dopant atoms is the essential transport mechanism. Furthermore, observation of individual dopant potential in the channel by Kelvin probe force microscopy is also presented. These results may pave the way for the development of a new device technology, i.e., single-dopant atom electronics.

No MeSH data available.


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KFM observation of discrete dopants in device channel. (a) Setup for LT-KFM measurements, showing in the inset the topography of the measured channel area. (b) Simulated surface electronic potential map due to ionized P donors in a thin Si layer. (c) Measured electronic potential maps at the surface of P-doped SOI-FETs (lower panels are line profiles through some of the dark spots, i.e., regions of lower electronic potential).
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Figure 5: KFM observation of discrete dopants in device channel. (a) Setup for LT-KFM measurements, showing in the inset the topography of the measured channel area. (b) Simulated surface electronic potential map due to ionized P donors in a thin Si layer. (c) Measured electronic potential maps at the surface of P-doped SOI-FETs (lower panels are line profiles through some of the dark spots, i.e., regions of lower electronic potential).

Mentions: We have utilized a special setup of KFM, which allows us to measure FETs fabricated on SOI wafers, at low temperatures (approximately 13 K), with the possibility of fully using external biases [see Figure 5a]. Applying an appropriate bias to the devices can induce depletion of the channel of free carriers, leaving behind immobile charges, i.e., ionized dopants. Depletion can be achieved more readily at low temperatures, at which intrinsic carrier concentration is negligible, allowing for a measurement of unscreened ionized dopants [15]. Expected results are shown in Figure 5b from a simulation of electronic potential due to a random distribution of phosphorus (P) donors in a thin Si layer. Using our low-temperature (LT)-KFM technique, we measured the discrete distribution of P donors in the channel of thin SOI-FETs [14], as shown in Figure 5c as electronic potential maps. A darker contrast indicates lower electronic potential, consistent with the presence of a positive phosphorus ion (P+). The spatial extension of the dark spots is typically below 10 nm, while the potential depth is on average a few tens of meV, as observed from insets in Figure 5c. These characteristics are in good agreement with properties of individual P donors, such as Bohr radius (rB ≅ 2.5 nm) and ground state energy (E0 = 44 meV). Acceptor impurities, such as boron (B), could also be observed when measuring weakly doped p-type Si samples [14]. These results prove the potential of the KFM technique to resolve the distribution of dopants in FET channels at single-dopant level. Our recent studies also demonstrate the ability of LT-KFM to detect different charge states of isolated or clustered donors [29].


Atom devices based on single dopants in silicon nanostructures.

Moraru D, Udhiarto A, Anwar M, Nowak R, Jablonski R, Hamid E, Tarido JC, Mizuno T, Tabe M - Nanoscale Res Lett (2011)

KFM observation of discrete dopants in device channel. (a) Setup for LT-KFM measurements, showing in the inset the topography of the measured channel area. (b) Simulated surface electronic potential map due to ionized P donors in a thin Si layer. (c) Measured electronic potential maps at the surface of P-doped SOI-FETs (lower panels are line profiles through some of the dark spots, i.e., regions of lower electronic potential).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211992&req=5

Figure 5: KFM observation of discrete dopants in device channel. (a) Setup for LT-KFM measurements, showing in the inset the topography of the measured channel area. (b) Simulated surface electronic potential map due to ionized P donors in a thin Si layer. (c) Measured electronic potential maps at the surface of P-doped SOI-FETs (lower panels are line profiles through some of the dark spots, i.e., regions of lower electronic potential).
Mentions: We have utilized a special setup of KFM, which allows us to measure FETs fabricated on SOI wafers, at low temperatures (approximately 13 K), with the possibility of fully using external biases [see Figure 5a]. Applying an appropriate bias to the devices can induce depletion of the channel of free carriers, leaving behind immobile charges, i.e., ionized dopants. Depletion can be achieved more readily at low temperatures, at which intrinsic carrier concentration is negligible, allowing for a measurement of unscreened ionized dopants [15]. Expected results are shown in Figure 5b from a simulation of electronic potential due to a random distribution of phosphorus (P) donors in a thin Si layer. Using our low-temperature (LT)-KFM technique, we measured the discrete distribution of P donors in the channel of thin SOI-FETs [14], as shown in Figure 5c as electronic potential maps. A darker contrast indicates lower electronic potential, consistent with the presence of a positive phosphorus ion (P+). The spatial extension of the dark spots is typically below 10 nm, while the potential depth is on average a few tens of meV, as observed from insets in Figure 5c. These characteristics are in good agreement with properties of individual P donors, such as Bohr radius (rB ≅ 2.5 nm) and ground state energy (E0 = 44 meV). Acceptor impurities, such as boron (B), could also be observed when measuring weakly doped p-type Si samples [14]. These results prove the potential of the KFM technique to resolve the distribution of dopants in FET channels at single-dopant level. Our recent studies also demonstrate the ability of LT-KFM to detect different charge states of isolated or clustered donors [29].

Bottom Line: Such technological trend brought us to a research stage on devices working with one or a few dopant atoms.In this work, we review our most recent studies on key atom devices with fundamental structures of silicon-on-insulator MOSFETs, such as single-dopant transistors, preliminary memory devices, single-electron turnstile devices and photonic devices, in which electron tunneling mediated by single dopant atoms is the essential transport mechanism.These results may pave the way for the development of a new device technology, i.e., single-dopant atom electronics.

View Article: PubMed Central - HTML - PubMed

Affiliation: Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Nakaku, Hamamatsu, 432-8011, Japan. romtabe@rie.shizuoka.ac.jp.

ABSTRACT
Silicon field-effect transistors have now reached gate lengths of only a few tens of nanometers, containing a countable number of dopants in the channel. Such technological trend brought us to a research stage on devices working with one or a few dopant atoms. In this work, we review our most recent studies on key atom devices with fundamental structures of silicon-on-insulator MOSFETs, such as single-dopant transistors, preliminary memory devices, single-electron turnstile devices and photonic devices, in which electron tunneling mediated by single dopant atoms is the essential transport mechanism. Furthermore, observation of individual dopant potential in the channel by Kelvin probe force microscopy is also presented. These results may pave the way for the development of a new device technology, i.e., single-dopant atom electronics.

No MeSH data available.


Related in: MedlinePlus