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Electric-field-assisted formation of an interfacial double-donor molecule in silicon nano-transistors.

Samanta A, Moraru D, Mizuno T, Tabe M - Sci Rep (2015)

Bottom Line: In this work, we identify pairs of donor atoms in the nano-channel of a silicon field-effect transistor and demonstrate merging of the donor-induced potential wells at the interface by applying vertical electric field.This is due to the decrease of the system's charging energy, as confirmed by Coulomb blockade simulations.These results represent the first experimental observation of electric-field-assisted formation of an interfacial double-donor molecule, opening a pathway for designing functional devices using multiple coupled dopant atoms.

View Article: PubMed Central - PubMed

Affiliation: Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8011, Japan.

ABSTRACT
Control of coupling of dopant atoms in silicon nanostructures is a fundamental challenge for dopant-based applications. However, it is difficult to find systems of only a few dopants that can be directly addressed and, therefore, experimental demonstration has not yet been obtained. In this work, we identify pairs of donor atoms in the nano-channel of a silicon field-effect transistor and demonstrate merging of the donor-induced potential wells at the interface by applying vertical electric field. This system can be described as an interfacial double-donor molecule. Single-electron tunneling current is used to probe the modification of the potential well. When merging occurs at the interface, the gate capacitance of the potential well suddenly increases, leading to an abrupt shift of the tunneling current peak to lower gate voltages. This is due to the decrease of the system's charging energy, as confirmed by Coulomb blockade simulations. These results represent the first experimental observation of electric-field-assisted formation of an interfacial double-donor molecule, opening a pathway for designing functional devices using multiple coupled dopant atoms.

No MeSH data available.


Related in: MedlinePlus

Transport characteristics for devices doped with lower and higher concentration.Contour plots of IDS (top panels) and d2IDS/dVFG2 (bottom panels) as a function of backgate voltage (VBG) and frontgate voltage (VFG) for two types of devices: (a,b) randomly doped with lower doping concentration (ND ≈ 1 × 1018 cm−3); (c,d) selectively-doped with higher doping concentration (ND > 1 × 1019 cm−3). All data is measured at T = 5.5 K and VDS = 5 mV. Regions of current shifts are marked by dashed rectangles in (a,b). IDS–VFG characteristics (VBG = 0 V) for the selectively-doped high-concentration FET are shown as a side panel in (c). In (d), within the complex pattern of fine traces, several anti-crossing structures are marked by dashed lines, suggesting interaction between two QDs. Zoom-in plots of two such regions [marked as (i) and (ii)] are presented in the right-side panels of (d).
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f4: Transport characteristics for devices doped with lower and higher concentration.Contour plots of IDS (top panels) and d2IDS/dVFG2 (bottom panels) as a function of backgate voltage (VBG) and frontgate voltage (VFG) for two types of devices: (a,b) randomly doped with lower doping concentration (ND ≈ 1 × 1018 cm−3); (c,d) selectively-doped with higher doping concentration (ND > 1 × 1019 cm−3). All data is measured at T = 5.5 K and VDS = 5 mV. Regions of current shifts are marked by dashed rectangles in (a,b). IDS–VFG characteristics (VBG = 0 V) for the selectively-doped high-concentration FET are shown as a side panel in (c). In (d), within the complex pattern of fine traces, several anti-crossing structures are marked by dashed lines, suggesting interaction between two QDs. Zoom-in plots of two such regions [marked as (i) and (ii)] are presented in the right-side panels of (d).

Mentions: Figure 4a shows a zoomed-in VFG-VBG diagram within the positive-VBG region, focusing only on the two lowest-VFG prominent current peaks. As a way to emphasize the fine features, a second-order derivative of the current as a function of VFG is also presented in Fig. 4b. The faint current trace below the main peak becomes more prominent in Fig. 4b. As explained earlier, such fine trace can be ascribed to another P-donor located in the vicinity of the main transport donor. From both figures, it can be clearly observed that the current traces suddenly shift to lower VFG in a range of positive VBG. The regions in which these current shifts occur are marked by dashed rectangles.


Electric-field-assisted formation of an interfacial double-donor molecule in silicon nano-transistors.

Samanta A, Moraru D, Mizuno T, Tabe M - Sci Rep (2015)

Transport characteristics for devices doped with lower and higher concentration.Contour plots of IDS (top panels) and d2IDS/dVFG2 (bottom panels) as a function of backgate voltage (VBG) and frontgate voltage (VFG) for two types of devices: (a,b) randomly doped with lower doping concentration (ND ≈ 1 × 1018 cm−3); (c,d) selectively-doped with higher doping concentration (ND > 1 × 1019 cm−3). All data is measured at T = 5.5 K and VDS = 5 mV. Regions of current shifts are marked by dashed rectangles in (a,b). IDS–VFG characteristics (VBG = 0 V) for the selectively-doped high-concentration FET are shown as a side panel in (c). In (d), within the complex pattern of fine traces, several anti-crossing structures are marked by dashed lines, suggesting interaction between two QDs. Zoom-in plots of two such regions [marked as (i) and (ii)] are presented in the right-side panels of (d).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663623&req=5

f4: Transport characteristics for devices doped with lower and higher concentration.Contour plots of IDS (top panels) and d2IDS/dVFG2 (bottom panels) as a function of backgate voltage (VBG) and frontgate voltage (VFG) for two types of devices: (a,b) randomly doped with lower doping concentration (ND ≈ 1 × 1018 cm−3); (c,d) selectively-doped with higher doping concentration (ND > 1 × 1019 cm−3). All data is measured at T = 5.5 K and VDS = 5 mV. Regions of current shifts are marked by dashed rectangles in (a,b). IDS–VFG characteristics (VBG = 0 V) for the selectively-doped high-concentration FET are shown as a side panel in (c). In (d), within the complex pattern of fine traces, several anti-crossing structures are marked by dashed lines, suggesting interaction between two QDs. Zoom-in plots of two such regions [marked as (i) and (ii)] are presented in the right-side panels of (d).
Mentions: Figure 4a shows a zoomed-in VFG-VBG diagram within the positive-VBG region, focusing only on the two lowest-VFG prominent current peaks. As a way to emphasize the fine features, a second-order derivative of the current as a function of VFG is also presented in Fig. 4b. The faint current trace below the main peak becomes more prominent in Fig. 4b. As explained earlier, such fine trace can be ascribed to another P-donor located in the vicinity of the main transport donor. From both figures, it can be clearly observed that the current traces suddenly shift to lower VFG in a range of positive VBG. The regions in which these current shifts occur are marked by dashed rectangles.

Bottom Line: In this work, we identify pairs of donor atoms in the nano-channel of a silicon field-effect transistor and demonstrate merging of the donor-induced potential wells at the interface by applying vertical electric field.This is due to the decrease of the system's charging energy, as confirmed by Coulomb blockade simulations.These results represent the first experimental observation of electric-field-assisted formation of an interfacial double-donor molecule, opening a pathway for designing functional devices using multiple coupled dopant atoms.

View Article: PubMed Central - PubMed

Affiliation: Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8011, Japan.

ABSTRACT
Control of coupling of dopant atoms in silicon nanostructures is a fundamental challenge for dopant-based applications. However, it is difficult to find systems of only a few dopants that can be directly addressed and, therefore, experimental demonstration has not yet been obtained. In this work, we identify pairs of donor atoms in the nano-channel of a silicon field-effect transistor and demonstrate merging of the donor-induced potential wells at the interface by applying vertical electric field. This system can be described as an interfacial double-donor molecule. Single-electron tunneling current is used to probe the modification of the potential well. When merging occurs at the interface, the gate capacitance of the potential well suddenly increases, leading to an abrupt shift of the tunneling current peak to lower gate voltages. This is due to the decrease of the system's charging energy, as confirmed by Coulomb blockade simulations. These results represent the first experimental observation of electric-field-assisted formation of an interfacial double-donor molecule, opening a pathway for designing functional devices using multiple coupled dopant atoms.

No MeSH data available.


Related in: MedlinePlus