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Tunneling in Systems of Coupled Dopant-Atoms in Silicon Nano-devices.

Moraru D, Samanta A, Tyszka K, Anh le T, Muruganathan M, Mizuno T, Jablonski R, Mizuta H, Tabe M - Nanoscale Res Lett (2015)

Bottom Line: One pathway to observe and characterize such fundamental operation is to focus on identifying isolated or coupled dopants in nanoscale silicon transistors, the building blocks of present electronics.We also discuss tunneling transport behavior based on the analysis of low-temperature I-V characteristics for devices representative for different regimes of doping concentration, i.e., different inter-dopant coupling strengths.This overview outlines the present status of the field, opening also directions toward practical implementation of dopant-atom devices.

View Article: PubMed Central - PubMed

Affiliation: Department of Electronics and Materials Science, Faculty of Engineering, Shizuoka University, Shizuoka, Japan. moraru.daniel@shizuoka.ac.jp.

ABSTRACT
Following the rapid development of the electronics industry and technology, it is expected that future electronic devices will operate based on functional units at the level of electrically active molecules or even atoms. One pathway to observe and characterize such fundamental operation is to focus on identifying isolated or coupled dopants in nanoscale silicon transistors, the building blocks of present electronics. Here, we review some of the recent progress in the research along this direction, with a focus on devices fabricated with simple and CMOS-compatible-processing technology. We present results from a scanning probe method (Kelvin probe force microscopy) which show direct observation of dopant-induced potential modulations. We also discuss tunneling transport behavior based on the analysis of low-temperature I-V characteristics for devices representative for different regimes of doping concentration, i.e., different inter-dopant coupling strengths. This overview outlines the present status of the field, opening also directions toward practical implementation of dopant-atom devices.

No MeSH data available.


Related in: MedlinePlus

Kelvin probe force microscopy of donor atoms. a KPFM measurement setup, showing a cantilever approached near the surface of a SOI-FET channel with the device under regular operation conditions. b A possible potential landscape induced by several isolated, ionized P-donors. c A possible potential landscape induced by a larger number of P-donors forming multiple-donor “clusters” (containing several donors located at distances smaller than 2 × rB from each other)
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Fig1: Kelvin probe force microscopy of donor atoms. a KPFM measurement setup, showing a cantilever approached near the surface of a SOI-FET channel with the device under regular operation conditions. b A possible potential landscape induced by several isolated, ionized P-donors. c A possible potential landscape induced by a larger number of P-donors forming multiple-donor “clusters” (containing several donors located at distances smaller than 2 × rB from each other)

Mentions: KPFM is a suitable technique for such measurements because its detection principle is based on sensing the electrostatic force between a metallic tip (cantilever) and any point charges located in the sample [21], as schematically illustrated in Fig. 1a. However, there are several conditions that must be met in order to be able to observe dopants in a transistor nano-channel [20, 22]. First, the dopants should be ionized, i.e., for the case of a phosphorus-doped device, electrons should be depleted from the channel. For that purpose, the SOI-FETs have the source and drain leads connected to the ground, while negative voltage is applied to the back gate (substrate Si) in order to remove the free electrons from the channel to the leads. Thus, ionized P-donors are left behind as fixed positive point charges. Second, in order to further remove unwanted screening effects due to thermally-activated carriers, the KPFM measurements can be carried out even at low temperatures in our system. Third, the Si layer should be passivated (to avoid dangling bonds and other defect states that could affect the measurement). Such passivation is done by thermal oxidation in our fabrication processes. However, the SiO2 layer should be thin enough (usually, ~1 nm) to allow for the cantilever to approach the Si surface at a distance at which the electrostatic force induced by the dopants located in the channel can still be detected with sufficiently high resolution.Fig. 1


Tunneling in Systems of Coupled Dopant-Atoms in Silicon Nano-devices.

Moraru D, Samanta A, Tyszka K, Anh le T, Muruganathan M, Mizuno T, Jablonski R, Mizuta H, Tabe M - Nanoscale Res Lett (2015)

Kelvin probe force microscopy of donor atoms. a KPFM measurement setup, showing a cantilever approached near the surface of a SOI-FET channel with the device under regular operation conditions. b A possible potential landscape induced by several isolated, ionized P-donors. c A possible potential landscape induced by a larger number of P-donors forming multiple-donor “clusters” (containing several donors located at distances smaller than 2 × rB from each other)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4582038&req=5

Fig1: Kelvin probe force microscopy of donor atoms. a KPFM measurement setup, showing a cantilever approached near the surface of a SOI-FET channel with the device under regular operation conditions. b A possible potential landscape induced by several isolated, ionized P-donors. c A possible potential landscape induced by a larger number of P-donors forming multiple-donor “clusters” (containing several donors located at distances smaller than 2 × rB from each other)
Mentions: KPFM is a suitable technique for such measurements because its detection principle is based on sensing the electrostatic force between a metallic tip (cantilever) and any point charges located in the sample [21], as schematically illustrated in Fig. 1a. However, there are several conditions that must be met in order to be able to observe dopants in a transistor nano-channel [20, 22]. First, the dopants should be ionized, i.e., for the case of a phosphorus-doped device, electrons should be depleted from the channel. For that purpose, the SOI-FETs have the source and drain leads connected to the ground, while negative voltage is applied to the back gate (substrate Si) in order to remove the free electrons from the channel to the leads. Thus, ionized P-donors are left behind as fixed positive point charges. Second, in order to further remove unwanted screening effects due to thermally-activated carriers, the KPFM measurements can be carried out even at low temperatures in our system. Third, the Si layer should be passivated (to avoid dangling bonds and other defect states that could affect the measurement). Such passivation is done by thermal oxidation in our fabrication processes. However, the SiO2 layer should be thin enough (usually, ~1 nm) to allow for the cantilever to approach the Si surface at a distance at which the electrostatic force induced by the dopants located in the channel can still be detected with sufficiently high resolution.Fig. 1

Bottom Line: One pathway to observe and characterize such fundamental operation is to focus on identifying isolated or coupled dopants in nanoscale silicon transistors, the building blocks of present electronics.We also discuss tunneling transport behavior based on the analysis of low-temperature I-V characteristics for devices representative for different regimes of doping concentration, i.e., different inter-dopant coupling strengths.This overview outlines the present status of the field, opening also directions toward practical implementation of dopant-atom devices.

View Article: PubMed Central - PubMed

Affiliation: Department of Electronics and Materials Science, Faculty of Engineering, Shizuoka University, Shizuoka, Japan. moraru.daniel@shizuoka.ac.jp.

ABSTRACT
Following the rapid development of the electronics industry and technology, it is expected that future electronic devices will operate based on functional units at the level of electrically active molecules or even atoms. One pathway to observe and characterize such fundamental operation is to focus on identifying isolated or coupled dopants in nanoscale silicon transistors, the building blocks of present electronics. Here, we review some of the recent progress in the research along this direction, with a focus on devices fabricated with simple and CMOS-compatible-processing technology. We present results from a scanning probe method (Kelvin probe force microscopy) which show direct observation of dopant-induced potential modulations. We also discuss tunneling transport behavior based on the analysis of low-temperature I-V characteristics for devices representative for different regimes of doping concentration, i.e., different inter-dopant coupling strengths. This overview outlines the present status of the field, opening also directions toward practical implementation of dopant-atom devices.

No MeSH data available.


Related in: MedlinePlus