Perforated contact electrode on vertical nanowire array
Inventors
Pehrsson, Pehr E • Field, Chistopher • In, Hyun Jin
Assignees
Publication Number
US-9422158-B2
Publication Date
2016-08-23
Expiration Date
2031-11-10
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Abstract
Disclosed herein is a structure having: a support, a plurality of nanowires perpendicular to the support, and an electrode in contact with a first end of each nanowire. Each nanowire has a second end in contact with the support. The electrode contains a plurality of perforations. The electrode contains a plurality of perforations. Also disclosed herein is a method of: providing the above support and nanowires; depositing a layer of a filler material that covers a portion of each nanowire and leaves a first end of each nanowire exposed; depositing a plurality of nanoparticles onto the filler material; depositing an electrode material on the nanoparticles, the ends of the nanowires, and any exposed filler material; and removing the nanoparticles and filler material to form an electrode in contact with the first end of each nanowire; wherein the electrode contains a plurality of perforations.
Core Innovation
The invention discloses a structure comprising a support, a plurality of nanowires perpendicular to the support with each nanowire having a second end in contact with the support, and an electrode in contact with the first end of each nanowire. The electrode contains a plurality of perforations, which are open spaces forming a straight line path normal to the support and completely through the electrode. This perforated electrode design allows gases or liquids to flow rapidly through the electrode and come into contact with the sensing nanowire region beneath.
The invention also discloses a method for forming such a structure. This method involves providing the support and nanowires, depositing a filler material that partially covers each nanowire leaving the first ends exposed, depositing nanoparticles on the filler material to define locations for perforations, depositing an electrode material on the nanoparticles, nanowire ends, and exposed filler material, and then removing the nanoparticles and filler material to leave behind an electrode with perforations in contact with the nanowires' first ends.
The problem being solved relates to challenges in creating sensor devices based on vertical nanowire arrays, specifically making reliable individual electrical connections to all nanowires while allowing rapid analyte access to the nanowires. Existing methods do not enable formation of a porous top contact electrode layer with holes of controllable size and distribution, which are critical for maximizing surface area exposure and minimizing response time caused by hindered diffusion. The invention addresses these issues by enabling the formation of a perforated electrode with controlled hole size and periodicity directly on ordered vertical nanowire arrays.
Claims Coverage
The patent contains multiple claims with two independent claims focusing on methods for forming perforated electrodes in nanowire arrays and structures incorporating such electrodes. The inventive features involve methods of forming perforated electrodes and the resulting nanowire array structures with improved electrical and sensing properties.
Method for forming a perforated electrode on vertical nanowires
A method comprising providing a structure with a support and perpendicular nanowires having their second ends on the support; depositing a filler material covering a portion of each nanowire but exposing their first ends; depositing nanoparticles on the filler material; depositing electrode material on nanoparticles, nanowire ends, and any exposed filler; and removing nanoparticles and filler to form an electrode in contact with each nanowire's first end, where the electrode contains a plurality of perforations.
Method for forming a perforated electrode on nanowires embedded in filler material
A method comprising providing a structure with mutually parallel nanowires immobilized in a filler material and having exposed first ends; depositing nanoparticles on the filler material side; depositing electrode material on nanoparticles, nanowire first ends, and exposed filler; and removing nanoparticles and filler to form a first electrode with perforations in contact with the first ends of nanowires.
The claims focus on methods to form a perforated electrode contacting vertical nanowire arrays by utilizing filler materials and nanoparticle templates to create controlled electrode perforations, and on the resulting structures with such perforated electrodes. These inventive features enable improved sensor functionality by combining controlled electrical contact to nanowires with enhanced analyte access through perforations.
Stated Advantages
The ability to form periodic perforations between nanowires by an automatic self-assembly process requiring no registration or alignment, allowing scale-up to large areas and entire wafers.
Improved gas sensor performance with fast response rates and high sensitivity due to geometry-enabled gas flow through the perforated electrode and nanowire array.
Control over hole properties such as pitch and diameter through adjustment of nanosphere sizes and etching time, allowing tunable electrode porosity.
Significantly faster sensor response compared to nonporous electrodes by enabling analytes to flow directly through the electrode to all nanowires in the array.
Massively parallel nanowire electrical connection reducing noise sources like 1/f noise and shot noise, yielding improved signal-to-noise ratios for sensing.
Documented Applications
Gas and liquid phase sensors for detection of chemical warfare agents, explosives, chemical or biological agents, and toxic industrial chemicals.
Sensors converting adsorbed molecules into electrical signals such as changes in resistance, voltage, current, frequency, or capacitance.
High sensitivity detection of nitrogen dioxide (NO2) and ammonia (NH3) gases at low parts-per-billion levels, including responses in humidified air environments.
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