Large-scale ordered 1D-nanomaterials arrays: Assembly or not? (original) (raw)
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Self-integration of nanowires into circuits via guided growth
Proceedings of the National Academy of Sciences, 2013
The ability to assemble discrete nanowires (NWs) with nanoscale precision on a substrate is the key to their integration into circuits and other functional systems. We demonstrate a bottom-up approach for massively parallel deterministic assembly of discrete NWs based on surface-guided horizontal growth from nanopatterned catalyst. The guided growth and the catalyst nanopattern define the direction and length, and the position of each NW, respectively, both with unprecedented precision and yield, without the need for postgrowth assembly. We used these highly ordered NW arrays for the parallel production of hundreds of independently addressable single-NW field-effect transistors, showing up to 85% yield of working devices. Furthermore, we applied this approach for the integration of 14 discrete NWs into an electronic circuit operating as a three-bit address decoder. These results demonstrate the feasibility of massively parallel "self-integration" of NWs into electronic circuits and functional systems based on guided growth. nanotechnology | nanolithography | self-assembly | nanoelectronics | 1D nanostructures T he sustained progress in semiconductor technology introduces new challenges associated with the scaling and functionality of nanosize components. In the face of these challenges, alternative unconventional device and fabrication concepts based on bottom-up assembly of synthetic nanostructures are being intensively explored (1). These nanostructures, such as quantum dots (2), nanotubes (3), and nanowires (NWs) (4), can be chemically synthesized with exquisite control over their structures and properties down to the atomic level. On the other hand, their self-assembly alone is unlikely to produce the arbitrary geometries and long-range order that are required for their integration into functional systems. To realize such systems, bottomup assembly may be used as a complementary step in a sequence of top-down fabrication processes. Such a hybrid top-down/ bottom-up approach can be based on the directed self-assembly of building blocks onto a lithographically produced template to fit the design of an integrated functional system. Thus, the building blocks integrate themselves into the system, as one of the layers in the overall design. Here we demonstrate the feasibility of this "self-integration" concept with the parallel fabrication of large numbers of devices and complex circuits, based on guided growth of horizontal NWs (5).
Large-Scale Hierarchical Organization of Nanowire Arrays for Integrated Nanosystems
Nano Letters, 2003
We review recent studies of solution-based hierarchical organization of nanowire building blocks. Nanowires have been aligned with controlled nanometer to micrometer scale separation using the Langmuir-Blodgett technique, transferred to planar substrates in a layer-by-layer process to form parallel and crossed nanowire structures over centimeter length scales, and then efficiently patterned into repeating arrays of controlled dimensions and pitch using photolithography. The hierarchically-organized nanowires open up key opportunities in several general areas of nanoscale science and technology. First, hierarchically-assembled nanowire arrays have been used as masks to define nanometer scale metal lines and surface features over large areas. Second, hierarchically-assembled nanowire arrays have been used to fabricate fully-scalable centimeter size arrays of field-effect transistors in high yields without requiring alignment of individual nanowires to output electrodes. Diverse applications of this approach for enabling a broad range of functional nanosystems, including macroelectronic and sensing applications, are described.
Wafer-Scale Assembly of Highly Ordered Semiconductor Nanowire Arrays by Contact Printing
Nano Letters, 2008
been one of the significant bottleneck challenges facing the potential integration of nanowires for both nano and macro electronic circuit applications. Many efforts have focused on tackling this challenge, and while significant progress has been made, still most presented approaches lack either the desired controllability in the positioning of nanowires or the needed uniformity over large scales. Here, we demonstrate wafer-scale assembly of highly ordered, dense, and regular arrays of NWs with high uniformity and reproducibility through a simple contact printing process. We demonstrate contact printing as a versatile strategy for direct transfer and controlled positioning of various NW materials into complex structural configurations on substrates. The assembled NW pitch is shown to be readily modulated through the surface chemical treatment of the receiver substrate, with the highest density approaching ~8 NW/µm, ~95% directional alignment and wafer-scale uniformity. Furthermore, we demonstrate that our printing approach enables large-scale integration of NW arrays for various device structures on both Si and plastic substrates, with a controlled semiconductor channel width, and therefore ON current, ranging from a single NW (~10 nm) and up to ~250 µm, consisting of a parallel array of over 1,250 NWs.
Scalable Interconnection and Integration of Nanowire Devices without Registration
Nano Letters, 2004
A general strategy for the parallel and scalable integration of nanowire devices over large areas without the need to register individual nanowire−electrode interconnects has been developed. The approach was implemented using a Langmuir−Blodgett method to organize nanowires with controlled alignment and spacing over large areas and photolithography to define interconnects. Centimeter-scale arrays containing thousands of single silicon nanowire field-effect transistors were fabricated in this way and were shown to exhibit both high performance with unprecedented reproducibility and scalability to at least the 100-nm level. Moreover, scalable device characteristics were demonstrated by interconnecting a controlled number of nanowires per transistor in "pixel-like" device arrays. The general applicability of this approach to other nanowire and nanotube building blocks could enable the assembly, interconnection, and integration of a broad range of functional nanosystems.
ACS Nano
Nanofabrication has been utilized to manufacture one-, two-, and threedimensional functional nanostructures for applications such as electronics, sensors, and photonic devices. Although conventional silicon-based nanofabrication (top-down approach) has developed into a technique with extremely high precision and integration density, nanofabrication based on directed assembly (bottom-up approach) is attracting more interest recently owing to its low cost and the advantages of additive manufacturing. Directed assembly is a process that utilizes external fields to directly interact with nanoelements (nanoparticles, 2D nanomaterials, nanotubes, nanowires, etc.) and drive the nanoelements to site-selectively assemble in patterned areas on substrates to form functional structures. Directed assembly processes can be divided into four different categories depending on the external fields: electric field-directed assembly, fluidic flowdirected assembly, magnetic field-directed assembly, and optical field-directed assembly. In this review, we summarize recent progress utilizing these four processes and address how these directed assembly processes harness the external fields, the underlying mechanism of how the external fields interact with the nanoelements, and the advantages and drawbacks of utilizing each method. Finally, we discuss applications made using directed assembly and provide a perspective on the future developments and challenges.
Bottom‐Up Assembly of Micro/Nanostructures
Advanced Materials Interfaces, 2020
approach to the construction of target structures to much larger scales, [6] thereby including the millimetric [7] and centimetric. [8] It is tempting to roughly quantify the popularity of self-assembly in recent scientific literature by means of a quick archive search by keyword: Figure 1 evidences a steep and almost constant rise of the number of documents containing "self-assembly" in the last 20 years. In the wake of the enduring interest and wealth of possibilities empowered by self-assembly, the purpose of this Special Issue was to create a collection of invited contributions that would highlight some of the most recent trends and appealing applications for bottom-up assembly at the micro-and nanoscale. ADMI offered kind hospitality to our ambition, and we consider the Issue very fitting for the interdisciplinary scope and audience of the journal-at the interface indeed between multiple fields and interests. A quick look at the Table of Contents reveals an emphasis on one of the most studied and versatile self-assembled materials, i.e., block copolymers and their multiple parametric properties, constellated by contributions on tuneable nanoparticle arrays, monolayer doping of nanowires, functionalization of polymer nanoparticle, capillary self-folding, and a glance into macroscopic self-assembly. What follows is a short introduction to each contribution. Nanowires are a notable example of nanoscale components whose functionality for, e.g., sensing and optoelectronic applications needs carefully controlled and highly uniform doping profiles. To address this challenge, a viable alternative to in situ doping (i.e., doping during nanowire growth) consists in using molecular monolayers as ex situ and self-limiting dopant sources. Methodologies for monolayer doping are advancing rapidly by virtue of research on improved surface chemistry, capping layers and annealing schedule to control doping levels. These works are accumulating a detailed knowledge of the dynamics of monolayer fragmentation at different stages of the doping process and of their impact on doping levels and uniformity. However, a comprehensive understanding of
ASSEMBLY AND CHALLENGES OF ONE DIMENSIONAL SEMICONDUCTOR NANOSTRUCTURES
Science and Engineering Journal, 2021
One-dimensional (1D) semiconductor nanostructure materials, for example, nanowires, nano belts and nano tubes, have acquired enormous consideration inside the last decade. Among the gigantic assortment of 1D nano structures, semiconducting nanowires have acquired specific interest because of their likely applications in optoelectronic and electronic gadgets. This review paper gives information of the late cycle in the get together of one-dimensional nanostructures into valuable models and outlines the development of novel device dependent on such plans. The survey article finishes up with an assessment of the exceptional logical difficulties in the field and brief remarks concerning the ecological and general medical problems encompassing one-dimensional nano materials.
Facile Integration of Ordered Nanowires in Functional Devices
The integration of one dimensional (1D) nanostructures of non-industry-standard semiconductors in functional devices following bottom-up approaches is still an open challenge that hampers the exploitation of all their potential. Here, we present a simple approach to integrate metal oxide nanowires in electronic devices based on controlled dielectrophoretic positioning together with proof of concept devices that corroborate their functionality. The method is flexible enough to manipulate nanowires of different sizes and compositions exclusively using macroscopic solution-based techniques in conventional electrode designs. Our results show that fully functional devices, which display all the advantages of single-nanowire gas sensors, photodetectors, and even field-effect transistors, are thus obtained right after a direct assembly step without subsequent metallization processing. This paves the way to low cost, high throughput manufacturing of general-purpose electronic devices based on non-conventional and high quality 1D nanostructures driving up many options for high performance and new low energy consumption devices.
Layer-by-Layer Assembly of Nanowires for Three-Dimensional, Multifunctional Electronics
Nano Letters, 2007
We report a general approach for three-dimensional (3D) multifunctional electronics based on the layer-by-layer assembly of nanowire (NW) building blocks. Using germanium/silicon (Ge/Si) core/shell NWs as a representative example, ten vertically stacked layers of multi-NW fieldeffect transistors (FETs) were fabricated. Transport measurements demonstrate that the Ge/Si NW FETs have reproducible high-performance device characteristics within a given device layer, that the FET characteristics are not affected by sequential stacking, and importantly, that uniform performance is achieved in sequential layers 1 through 10 of the 3D structure. Five-layer single-NW FET structures were also prepared by printing Ge/Si NWs from lower density growth substrates, and transport measurements showed similar high-performance characteristics for the FETs in layers 1 and 5. In addition, 3D multifunctional circuitry was demonstrated on plastic substrates with sequential layers of inverter logical gates and floating gate memory elements. Notably, electrical characterization studies show stable writing and erasing of the NW floating gate memory elements and demonstrate signal inversion with larger than unity gain for frequencies up to at least 50 MHz. The ability to assemble reproducibly sequential layers of distinct types of NW-based devices coupled with the breadth of NW building blocks should enable the assembly of increasing complex multilayer and multifunctional 3D electronics in the future.
Applied Physics Letters, 2007
The authors demonstrate precise alignment and controlled assembly of single wall nanotube ͑SWNT͒ bundles at a fast rate over large areas by combining electrophoresis and dip coating processes. SWNTs in solution are assembled on prepatterned features that are 80 nm wide and separated by 200 nm. The results show that the direction of substrate withdrawal significantly affects the orientation and alignment of the assembled SWNT bundles. I-V characterization is carried out to demonstrate electrical continuity of these assembled SWNT bundles.