On-film formation of nanowires

A route to defect-free nanowire growth and device fabrication

Jin Seo Noh, Wooyoung Shim, Jinhee Ham, Wooyoung Lee

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

Figure 5.3 TEM images and diffraction pattern of the cross section of a Bi nanowire - Bi thin film. (a) TEM image of the cross section of the Bi nanowire grown on a Bi thin film. (b) Magnified image of the Bi nanowire grown at a grain of the Bi thin film [4]. 5.3.2 Bismuth Telluride NanowiresBismuth telluride (Bi2Te3) is the most widely used thermoelectric material whose thermoelectric figure-of-merit, ZT, is approximately 1 at room temperature. It is also recognized as an important topological insulator, which shows nearly perfect electrical conduction on the surface in contrast to insulator-like behavior in the bulk [6]. Similar to Bi, low dimensional Bi2Te3 exhibits greatly enhanced thermoelectric performance. Venkatasubramanian et al., for example, demonstrated ZT ~ 2.3 for Bi2Te3/Sb2Te3 superlattices [7]. Low-dimensional Bi2Te3 structures are equally important for the study of topological insulators because surface states in low-dimensional structures become significant as the surface-to-volume ratio increases. The OFF-ON method can be used for the growth of high quality Bi2Te3 nanowires. Two different approaches are used: a one-step process and a two-step process. The one-step process refers to the use of the same experimental protocol as for the Bi nanowire growth, as represented in Fig. 5.4a [8]. First, a BiTe thin film is deposited onto a Si substrate with a SiO2 overlayer, normally by sputtering. Either sputtering from a BiTe compound target or co-sputtering from separate Bi and Te elemental targets can be used for this purpose. The BiTe film thickness is controlled in the range of 40 to 100 nm. In the next step, the BiTe film on the substrate undergoes vacuum-annealing at a high temperature. The annealing temperature should be set higher than that for Bi nanowire growth because of the higher melting point of Bi2Te3 (585°C). The annealing temperatures should be between 300°C and 400°C. The BiTe film expands more than the substrate does, as indicated by its thermal expansion coefficient (~13.4 × 10-6/°C) which is larger than the thermal expansion coefficient of the substrate ((0.5 × 10-6/°C)/(2.4 × 10-6/°C)). The compressive stress induced in the BiTe film is the driving force for Bi2Te3 nanowire growth, as it is for Bi nanowire growth. It has been demonstrated that Bi2Te3 nanowires grown by this method are highly single-crystalline and uniform in diameter without tapering. The growth mechanism and characterization of Bi2Te3 nanowires grown by the OFF-ON method is described in Ref. [8].

Original languageEnglish
Title of host publicationVistas in Nanofabrication
PublisherPan Stanford Publishing Pte. Ltd.
Pages97-114
Number of pages18
ISBN (Electronic)9789814364577
ISBN (Print)9789814364560
DOIs
Publication statusPublished - 2012 Jan 1

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Nanowires
Fabrication
Defects
Sputtering
Thin films
Substrates
Annealing
Thermal expansion
Transmission electron microscopy
Temperature
Superlattices
Surface states
Bismuth
Compressive stress
Diffraction patterns
Melting point
Film thickness
Vacuum
Crystalline materials

All Science Journal Classification (ASJC) codes

  • Engineering(all)
  • Materials Science(all)

Cite this

Noh, J. S., Shim, W., Ham, J., & Lee, W. (2012). On-film formation of nanowires: A route to defect-free nanowire growth and device fabrication. In Vistas in Nanofabrication (pp. 97-114). Pan Stanford Publishing Pte. Ltd.. https://doi.org/10.1201/b12779
Noh, Jin Seo ; Shim, Wooyoung ; Ham, Jinhee ; Lee, Wooyoung. / On-film formation of nanowires : A route to defect-free nanowire growth and device fabrication. Vistas in Nanofabrication. Pan Stanford Publishing Pte. Ltd., 2012. pp. 97-114
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Noh, JS, Shim, W, Ham, J & Lee, W 2012, On-film formation of nanowires: A route to defect-free nanowire growth and device fabrication. in Vistas in Nanofabrication. Pan Stanford Publishing Pte. Ltd., pp. 97-114. https://doi.org/10.1201/b12779

On-film formation of nanowires : A route to defect-free nanowire growth and device fabrication. / Noh, Jin Seo; Shim, Wooyoung; Ham, Jinhee; Lee, Wooyoung.

Vistas in Nanofabrication. Pan Stanford Publishing Pte. Ltd., 2012. p. 97-114.

Research output: Chapter in Book/Report/Conference proceedingChapter

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T1 - On-film formation of nanowires

T2 - A route to defect-free nanowire growth and device fabrication

AU - Noh, Jin Seo

AU - Shim, Wooyoung

AU - Ham, Jinhee

AU - Lee, Wooyoung

PY - 2012/1/1

Y1 - 2012/1/1

N2 - Figure 5.3 TEM images and diffraction pattern of the cross section of a Bi nanowire - Bi thin film. (a) TEM image of the cross section of the Bi nanowire grown on a Bi thin film. (b) Magnified image of the Bi nanowire grown at a grain of the Bi thin film [4]. 5.3.2 Bismuth Telluride NanowiresBismuth telluride (Bi2Te3) is the most widely used thermoelectric material whose thermoelectric figure-of-merit, ZT, is approximately 1 at room temperature. It is also recognized as an important topological insulator, which shows nearly perfect electrical conduction on the surface in contrast to insulator-like behavior in the bulk [6]. Similar to Bi, low dimensional Bi2Te3 exhibits greatly enhanced thermoelectric performance. Venkatasubramanian et al., for example, demonstrated ZT ~ 2.3 for Bi2Te3/Sb2Te3 superlattices [7]. Low-dimensional Bi2Te3 structures are equally important for the study of topological insulators because surface states in low-dimensional structures become significant as the surface-to-volume ratio increases. The OFF-ON method can be used for the growth of high quality Bi2Te3 nanowires. Two different approaches are used: a one-step process and a two-step process. The one-step process refers to the use of the same experimental protocol as for the Bi nanowire growth, as represented in Fig. 5.4a [8]. First, a BiTe thin film is deposited onto a Si substrate with a SiO2 overlayer, normally by sputtering. Either sputtering from a BiTe compound target or co-sputtering from separate Bi and Te elemental targets can be used for this purpose. The BiTe film thickness is controlled in the range of 40 to 100 nm. In the next step, the BiTe film on the substrate undergoes vacuum-annealing at a high temperature. The annealing temperature should be set higher than that for Bi nanowire growth because of the higher melting point of Bi2Te3 (585°C). The annealing temperatures should be between 300°C and 400°C. The BiTe film expands more than the substrate does, as indicated by its thermal expansion coefficient (~13.4 × 10-6/°C) which is larger than the thermal expansion coefficient of the substrate ((0.5 × 10-6/°C)/(2.4 × 10-6/°C)). The compressive stress induced in the BiTe film is the driving force for Bi2Te3 nanowire growth, as it is for Bi nanowire growth. It has been demonstrated that Bi2Te3 nanowires grown by this method are highly single-crystalline and uniform in diameter without tapering. The growth mechanism and characterization of Bi2Te3 nanowires grown by the OFF-ON method is described in Ref. [8].

AB - Figure 5.3 TEM images and diffraction pattern of the cross section of a Bi nanowire - Bi thin film. (a) TEM image of the cross section of the Bi nanowire grown on a Bi thin film. (b) Magnified image of the Bi nanowire grown at a grain of the Bi thin film [4]. 5.3.2 Bismuth Telluride NanowiresBismuth telluride (Bi2Te3) is the most widely used thermoelectric material whose thermoelectric figure-of-merit, ZT, is approximately 1 at room temperature. It is also recognized as an important topological insulator, which shows nearly perfect electrical conduction on the surface in contrast to insulator-like behavior in the bulk [6]. Similar to Bi, low dimensional Bi2Te3 exhibits greatly enhanced thermoelectric performance. Venkatasubramanian et al., for example, demonstrated ZT ~ 2.3 for Bi2Te3/Sb2Te3 superlattices [7]. Low-dimensional Bi2Te3 structures are equally important for the study of topological insulators because surface states in low-dimensional structures become significant as the surface-to-volume ratio increases. The OFF-ON method can be used for the growth of high quality Bi2Te3 nanowires. Two different approaches are used: a one-step process and a two-step process. The one-step process refers to the use of the same experimental protocol as for the Bi nanowire growth, as represented in Fig. 5.4a [8]. First, a BiTe thin film is deposited onto a Si substrate with a SiO2 overlayer, normally by sputtering. Either sputtering from a BiTe compound target or co-sputtering from separate Bi and Te elemental targets can be used for this purpose. The BiTe film thickness is controlled in the range of 40 to 100 nm. In the next step, the BiTe film on the substrate undergoes vacuum-annealing at a high temperature. The annealing temperature should be set higher than that for Bi nanowire growth because of the higher melting point of Bi2Te3 (585°C). The annealing temperatures should be between 300°C and 400°C. The BiTe film expands more than the substrate does, as indicated by its thermal expansion coefficient (~13.4 × 10-6/°C) which is larger than the thermal expansion coefficient of the substrate ((0.5 × 10-6/°C)/(2.4 × 10-6/°C)). The compressive stress induced in the BiTe film is the driving force for Bi2Te3 nanowire growth, as it is for Bi nanowire growth. It has been demonstrated that Bi2Te3 nanowires grown by this method are highly single-crystalline and uniform in diameter without tapering. The growth mechanism and characterization of Bi2Te3 nanowires grown by the OFF-ON method is described in Ref. [8].

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Noh JS, Shim W, Ham J, Lee W. On-film formation of nanowires: A route to defect-free nanowire growth and device fabrication. In Vistas in Nanofabrication. Pan Stanford Publishing Pte. Ltd. 2012. p. 97-114 https://doi.org/10.1201/b12779