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Integrated sensitive on-chip ion field effect transistors based on wrinkled InGaAs nanomembranes.

Harazim SM, Feng P, Sanchez S, Deneke C, Mei Y, Schmidt OG - Nanoscale Res Lett (2011)

Bottom Line: Self-organized wrinkling of pre-strained nanomembranes into nanochannels is used to fabricate a fully integrated nanofluidic device for the development of ion field effect transistors (IFETs).Constrained by the structure and shape of the membrane, the deterministic wrinkling process leads to a versatile variation of channel types such as straight two-way channels, three-way branched channels, or even four-way intersection channels.The fabrication of straight channels is well controllable and offers the opportunity to integrate multiple IFET devices into a single chip.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany. s.harazim@ifw-dresden.de.

ABSTRACT
Self-organized wrinkling of pre-strained nanomembranes into nanochannels is used to fabricate a fully integrated nanofluidic device for the development of ion field effect transistors (IFETs). Constrained by the structure and shape of the membrane, the deterministic wrinkling process leads to a versatile variation of channel types such as straight two-way channels, three-way branched channels, or even four-way intersection channels. The fabrication of straight channels is well controllable and offers the opportunity to integrate multiple IFET devices into a single chip. Thus, several IFETs are fabricated on a single chip using a III-V semiconductor substrate to control the ion separation and to measure the ion current of a diluted potassium chloride electrolyte solution.

No MeSH data available.


Related in: MedlinePlus

Versatility of wrinkling. Alternative wrinkling structures leading to different channel arrangements such as (a) multiple openings for circular mesa structures and (b) parallel alignment of channels for stripe-like mesa structures. (c) An SEM image of a squared GaAs mesa structure with a wrinkled In0.2Ga0.8As layer on top. (d) An SEM/FIB cut image of one wrinkled nanochannel. The carbon cover protects the wrinkled structure during the FIB cut. Unlabeled scale bars are 2 μm.
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Figure 4: Versatility of wrinkling. Alternative wrinkling structures leading to different channel arrangements such as (a) multiple openings for circular mesa structures and (b) parallel alignment of channels for stripe-like mesa structures. (c) An SEM image of a squared GaAs mesa structure with a wrinkled In0.2Ga0.8As layer on top. (d) An SEM/FIB cut image of one wrinkled nanochannel. The carbon cover protects the wrinkled structure during the FIB cut. Unlabeled scale bars are 2 μm.

Mentions: The improved REBOLA technique uses small strained InGaAs membranes on mesa structures which allows for the exact on-chip placement of the nanochannels. In order to have an accurate and reproducible channel alignment and to identify the most suitable wrinkling behavior for the fabrication of straight nanochannels, the wrinkling of different InGaAs membrane shapes were investigated. We aimed for the fabrication of square, circular, and stripe-shaped membranes as shown in Figure 4. Mesa structures with circular or stripe shapes lead to straight channel structures, but they also offer a bigger variety of channel types with different alignments. For an example, a circular shape with a diameter of 6 μm gives a more random distribution of the channel orientations and even different types channels themselves (Figure 4a). The most observed channel types are straight channels; nonetheless, three-way channels as well as four-way channels appear in a numerous quantity. For stripe-like mesa structures with a width of about 6 μm and a length of several tens of micrometers, parallel channels can be realized (Figure 4b). Only square-shaped InGaAs layers wrinkle almost in the same orientation every time and, therefore, this kind of structure has been used as the base pattern for the device assembling (Figure 4c). This preferred wrinkle orientation relies on the crystal structure of the sacrificial AlAs layer and the different HF etching rates along the crystal axis [8,18]. Due to the MBE layer growth, the AlAs crystal structure is similar to the substrate which is GaAs(001). The etching rates are highest perpendicular to the <110> direction of the crystal. Assuming that the edges of the functional InGaAs membrane are aligned to the <110> direction of the substrate, the two faster under-etched edges will bond back to the substrate prior to the two edges with a lower etching rate. This etching rate preference, fixes the wrinkle orientation of any square-shaped nanomembrane parallel to the <110> direction. A focused ion beam (FIB) cut of a straight two-way nanochannel is shown in Figure 4d, where the internal structure of the InGaAs wrinkles can be observed. The benefits of the self-organized wrinkling of strained InGaAs nanomembranes into nanofluidic channels are the integration into a semiconductor substrate with accurate control of location, channel type, and the orientation on the chip.


Integrated sensitive on-chip ion field effect transistors based on wrinkled InGaAs nanomembranes.

Harazim SM, Feng P, Sanchez S, Deneke C, Mei Y, Schmidt OG - Nanoscale Res Lett (2011)

Versatility of wrinkling. Alternative wrinkling structures leading to different channel arrangements such as (a) multiple openings for circular mesa structures and (b) parallel alignment of channels for stripe-like mesa structures. (c) An SEM image of a squared GaAs mesa structure with a wrinkled In0.2Ga0.8As layer on top. (d) An SEM/FIB cut image of one wrinkled nanochannel. The carbon cover protects the wrinkled structure during the FIB cut. Unlabeled scale bars are 2 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 4: Versatility of wrinkling. Alternative wrinkling structures leading to different channel arrangements such as (a) multiple openings for circular mesa structures and (b) parallel alignment of channels for stripe-like mesa structures. (c) An SEM image of a squared GaAs mesa structure with a wrinkled In0.2Ga0.8As layer on top. (d) An SEM/FIB cut image of one wrinkled nanochannel. The carbon cover protects the wrinkled structure during the FIB cut. Unlabeled scale bars are 2 μm.
Mentions: The improved REBOLA technique uses small strained InGaAs membranes on mesa structures which allows for the exact on-chip placement of the nanochannels. In order to have an accurate and reproducible channel alignment and to identify the most suitable wrinkling behavior for the fabrication of straight nanochannels, the wrinkling of different InGaAs membrane shapes were investigated. We aimed for the fabrication of square, circular, and stripe-shaped membranes as shown in Figure 4. Mesa structures with circular or stripe shapes lead to straight channel structures, but they also offer a bigger variety of channel types with different alignments. For an example, a circular shape with a diameter of 6 μm gives a more random distribution of the channel orientations and even different types channels themselves (Figure 4a). The most observed channel types are straight channels; nonetheless, three-way channels as well as four-way channels appear in a numerous quantity. For stripe-like mesa structures with a width of about 6 μm and a length of several tens of micrometers, parallel channels can be realized (Figure 4b). Only square-shaped InGaAs layers wrinkle almost in the same orientation every time and, therefore, this kind of structure has been used as the base pattern for the device assembling (Figure 4c). This preferred wrinkle orientation relies on the crystal structure of the sacrificial AlAs layer and the different HF etching rates along the crystal axis [8,18]. Due to the MBE layer growth, the AlAs crystal structure is similar to the substrate which is GaAs(001). The etching rates are highest perpendicular to the <110> direction of the crystal. Assuming that the edges of the functional InGaAs membrane are aligned to the <110> direction of the substrate, the two faster under-etched edges will bond back to the substrate prior to the two edges with a lower etching rate. This etching rate preference, fixes the wrinkle orientation of any square-shaped nanomembrane parallel to the <110> direction. A focused ion beam (FIB) cut of a straight two-way nanochannel is shown in Figure 4d, where the internal structure of the InGaAs wrinkles can be observed. The benefits of the self-organized wrinkling of strained InGaAs nanomembranes into nanofluidic channels are the integration into a semiconductor substrate with accurate control of location, channel type, and the orientation on the chip.

Bottom Line: Self-organized wrinkling of pre-strained nanomembranes into nanochannels is used to fabricate a fully integrated nanofluidic device for the development of ion field effect transistors (IFETs).Constrained by the structure and shape of the membrane, the deterministic wrinkling process leads to a versatile variation of channel types such as straight two-way channels, three-way branched channels, or even four-way intersection channels.The fabrication of straight channels is well controllable and offers the opportunity to integrate multiple IFET devices into a single chip.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany. s.harazim@ifw-dresden.de.

ABSTRACT
Self-organized wrinkling of pre-strained nanomembranes into nanochannels is used to fabricate a fully integrated nanofluidic device for the development of ion field effect transistors (IFETs). Constrained by the structure and shape of the membrane, the deterministic wrinkling process leads to a versatile variation of channel types such as straight two-way channels, three-way branched channels, or even four-way intersection channels. The fabrication of straight channels is well controllable and offers the opportunity to integrate multiple IFET devices into a single chip. Thus, several IFETs are fabricated on a single chip using a III-V semiconductor substrate to control the ion separation and to measure the ion current of a diluted potassium chloride electrolyte solution.

No MeSH data available.


Related in: MedlinePlus