Rockville, MD, United States
Rockville, MD, United States

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Josell D.,U.S. National Institute of Standards and Technology | Debnath R.,U.S. National Institute of Standards and Technology | Debnath R.,N5 Sensors, Inc. | Ha J.Y.,U.S. National Institute of Standards and Technology | And 6 more authors.
ACS Applied Materials and Interfaces | Year: 2014

This study presents windowless CdSe/CdTe thin film photovoltaic devices with in-plane patterning at a submicrometer length scale. The photovoltaic cells are fabricated upon two interdigitated comb electrodes prepatterned at micrometer length scale on an insulating substrate. CdSe is electrodeposited on one electrode, and CdTe is deposited by pulsed laser deposition over the entire surface of the resulting structure. Previous studies of symmetric devices are extended in this study. Specifically, device performance is explored with asymmetric devices having fixed CdTe contact width and a range of CdSe contact widths, and the devices are fabricated with improved dimensional tolerance. Scanning photocurrent microscopy (also known as laser beam induced current mapping) is used to examine local current collection efficiency, providing information on the spatial variation of performance that complements current-voltage and external quantum efficiency measurements of overall device performance. Modeling of carrier transport and recombination indicates consistency of experimental results for local and blanket illumination. Performance under simulated air mass 1.5 illumination exceeds 5% for all dimensions examined, and the best-performing device achieved 5.9% efficiency. © 2014 American Chemical Society.


Hangarter C.M.,U.S. National Institute of Standards and Technology | Debnath R.,U.S. National Institute of Standards and Technology | Debnath R.,University of Maryland University College | Debnath R.,N5 Sensors, Inc. | And 6 more authors.
ACS Applied Materials and Interfaces | Year: 2013

This paper details the use of scanning photocurrent microscopy to examine localized current collection efficiency of thin-film photovoltaic devices with in-plane patterning at a submicrometer length scale. The devices are based upon two interdigitated comb electrodes at the micrometer length scale prepatterned on a substrate, with CdSe electrodeposited on one electrode and CdTe deposited over the entire surface of the resulting structure by pulsed laser deposition. Photocurrent maps provide information on what limits the performance of the windowless CdSe/CdTe thin-film photovoltaic devices, revealing "dead zones" particularly above the electrodes contacting the CdTe which is interpreted as recombination over the back contact. Additionally, the impact of ammonium sulfide passivation is examined, which enables device efficiency to reach 4.3% under simulated air mass 1.5 illumination. © 2013 American Chemical Society.


Grant
Agency: Department of Defense | Branch: Army | Program: STTR | Phase: Phase I | Award Amount: 149.31K | Year: 2014

The proposed project will demonstrate high-frequency (0.5 5 GHz) operation of novel 2-dimensional semiconductor molybdinum disulphide (MoS2) based field-effect transistors. Our project will focus on innovative growth startegies for large-area growth of MoS2 along with novel device design methodologies which will consider the tradeoffs between monolayer and multilayer device designs for high-frequency applications. Although in recent years studies have indicated exciting possibilities of the 2-D materials, significant challenges remain in realizing useful devices. Most of the efforts concentrate only on the superior properties of the 2-D channel material. The device performance in 2D materials will be largely dominated by contacts and the interfaces. The issue of device engineering and design using these 2D materials should include detailed interface physics and role of contact parasitics. In collaboration with George Mason University, N5 will develop large-area growth strategies, understanding the device physics and engineering including the role of interface transport with detailed characterization of defects and the effect of contact properties. The end goal of this project is to demonstrate the feasibility of high-frequency transistors realized using MoS2 materials. Key components of our approach are: 1) large-area growth of mono and multi-layer MoS2 layers using chemical vapor deposition methods with emphasis on large-area uniformity and reproducibility, 2) fabrication of large-periphery RF devices utilizing only conventional fabrication methods using contact or projection lithography for high throughput device manufacturing, and 3) high-frequency operation through innovations in source/drain contact engineering, gate dielectrics, and novel concept of"layer engineering".


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: STTR | Phase: Phase I | Award Amount: 120.39K | Year: 2015

Extravehicular Mobility Units (EVU) are the necessary to perform elaborate, dynamic tasks in the biologically harsh conditions of space from International Space Station (ISS) external repairs to human exploration of planetary bodies. The EVUs have stringent requirements on physical and chemical nature of the equipment/components/processes, to ensure safety and health of the individual require proper functioning of its life-support systems. Monitoring the Portable Life Support System (PLSS) of the EVU in real time is to ensure the safety of the astronaut and success of the mission.N5 Sensors will demonstrate an ultra-small form factor, highly reliable, rugged, low-power sensor architecture that is ideally suited for monitoring trace chemicals in spacecraft environment. This will be accomplished by our patent-pending innovation in photo-enabled sensing utilizing a hybrid chemiresistor architecture, which combines the selective adsorption properties of multicomponent (metal-oxide and metal) photocatalytic nanoclusters together with the sensitive transduction capability of sub-micron semiconductor gallium nitride (GaN) photoconductors. For the phase I project we will demonstrate oxygen, carbon dioxide, and ammonia sensor elements on a single chip. Innovative GaN photoconductor design will enable high-sensitivity, low power consumption, and self-calibration for the sensor current drift. The multicomponent nanocluster layer design enables room-temperature sensing with high selectivity, resulting in significant power saving and enhanced reliability. The fabrication of the sensors will be done using traditional photolithography and plasma etching. The nanocluster functionalization layer will be deposited using sputtering methods. The sensor testing will be carried out to determine sensing range, sensitivity, selective, and response/recovery times.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: STTR | Phase: Phase II | Award Amount: 749.75K | Year: 2017

Extravehicular Mobility Units (EVU) are the necessary to perform elaborate, dynamic tasks in the biologically harsh conditions of space and they have stringent requirements on physical and chemical nature of the equipment/components/processes, to ensure safety and health of the individual require proper functioning of its life-support systems. Monitoring the Portable Life Support System (PLSS) of the EVU in real time ensures the safety of the astronaut and success of the mission. In Phase I, N5 Sensors has demonstrated and manufactured an ultra-small form factor, highly reliable, rugged, low-power sensor architecture for carbon dioxide (CO2) and ammonia (NH3) that is ideally suited for monitoring trace chemicals in spacesuite environment in presence of humidity and oxygen. N5 will perform additional design refinements in Phase II and implement on-chip components for enhanced analytical and operational reliability. Additionally, a complete detector system will be designed, integrated with various electronic components and tested to determine system level performance and reliability. Subsequent design refinements will be done.


Grant
Agency: National Science Foundation | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 148.85K | Year: 2014

The broader impact/commercial potential of this project is in various applications requiring real-time detection of toxic, explosive, and other harmful chemicals in a variety of environments. This innovative chemical sensor technology promises single-chip multianalyte sensors with significant cost savings resulting from enhanced performance, reliability, and lifetime. Developing ultra-small chemical detectors capable of detecting various toxic and hazardous chemicals in air reliably is essential in safeguarding individuals and communities. Such ultra-small multianalyte detectors could save lives of industrial workers and fire-fighters by making them more aware of their dangerous surrounding. Also next-generation of cloud-based, crowd-sourced, large-area sensor networks for urban monitoring can protect our communities from terrorist attacks. The diversity of potential industrial, environmental, and safety monitoring applications ensures sustainable growth paths in various domestic and international gas detection markets. The scientific component of this project will enhance the understanding of the complex processes occurring at the surfaces of these novel multicomponent nanoclusters, which could have profound impact in various other fields including photovoltaic, energy storage, and catalytic pollution-remediation. This Small Business Innovation Research (SBIR) Phase I project will demonstrate single-chip ammonia (NH3) and carbon monoxide (CO) sensors using patent-pending innovation in multicomponent photocatalytic nanocluster-based hybrid sensor technology. Both NH3 and CO are toxic industrial chemicals with very serious health hazards, and often present in various industrial, farming, agricultural, and transportation related activities. High-performance mobile devices used in various operational situations represent a powerful infrastructure which could be leveraged for chemical monitoring. Due to their size and power requirement, traditional sensors are not suitable for mobile-platform deployment. Single-chip, ultra low-power selective detection of NH3 and CO will be a significant accomplishment towards the goal of development of mobile devices based multithreat monitors that can be used by industrial workers, civilians, first-responders, and soldiers for both personal safety and infrastructural security.


Grant
Agency: Department of Homeland Security | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 99.73K | Year: 2014

The proposed SBIR phase I project will demonstrate a ultra-small, low-power, low-cost solution for detection of toxic gases and particulate matter (PM) in air. Firefighters are exposed to various toxic gases and PM both during active knock-down and overhaul phases of fire operation. Four-gas toxic monitors, commonly used by firefighters, are ineffective due to limited information it can provide, their large footprint, high power consumption, and high operational and maintenance cost. All those detectors are built using mature sensor technologies (such as catalytic, electrochemical, and photo-ionization detectors)and have severe operational and reliability drawbacks. N5 Sensors will demonstrate a chip-scale chemical sensor architecture that is ideally suited for detection of large number of toxic gases. This will be accomplished by our patent-pending innovation in photo-enabled sensing - which combines the selective adsorption properties of multicomponent photocatalytic nanoclusters together with the sensitive transduction capability of microscale photoconductors formed using standard highly scalable microfabrication processes. This key innovation enables the sensors to operate with very little power and be completely free from cross-sensitivity to other gases. By combining our innovated sensor chips with low-cost, commercial-off-the-shell PM detector, we will demonstrate a multi-gas and PM detector that can monitor 13 gases and PM of 2.5 and 10 micrometer aerodynamic diameters, with significant reduction in SWAP (Size-Wight-And-Power) and cost.


Grant
Agency: Department of Homeland Security | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 749.24K | Year: 2015

The proposed SBIR Phase II project will demonstrate a wearable, low-power, low-cost detector module capable of detecting 13 toxic and hazardous gases and particulate matter (PM) in air suitable for use by first-responders and fire-inspectors during active knock-down and overhaul phases of fire operation. Standard four-gas detectors are grossly inadequate not only in terms of the limited information they can provide, but also due to severe operational and reliability problems as well as high operational and maintenance costs. We will develop the detector by combining patent-pending chip-scale gas sensor technology with a low-cost PM detector module, resulting in an integrated solution for environmental threat monitoring. This microscale gas sensor technology relies on a nanophotocatalysts surface functionalization technique which allows for the detection of host of gases. Utilizing only a few sensor chips, small detectors capable of simultaneously monitoring multiple gases will be realized. These chip-scale microsensors are produced using highly-scalable microfabrication methods similar to those used in production of electronic integrated circuits, which are ideally-suited for low-cost mass-manufacturing. In addition, N5 will refine the sensor designs, introduce additional on-chip components for reliable field-operation, develop a robust manufacturing process, demonstrate the reliability metrics of these sensors, and develop three complete working prototype detectors. We will conduct field-testing of the completed handheld systems through various collaborations to gain insights into the operational, reliability, and maintenance issues, and explore strategies for seamless integration with the next-generation of incident command response and decision support systems.


Grant
Agency: NSF | Branch: Standard Grant | Program: | Phase: SMALL BUSINESS PHASE I | Award Amount: 166.24K | Year: 2014

The broader impact/commercial potential of this project is in various applications requiring real-time detection of toxic, explosive, and other harmful chemicals in a variety of environments. This innovative chemical sensor technology promises single-chip multianalyte sensors with significant cost savings resulting from enhanced performance, reliability, and lifetime. Developing ultra-small chemical detectors capable of detecting various toxic and hazardous chemicals in air reliably is essential in safeguarding individuals and communities. Such ultra-small multianalyte detectors could save lives of industrial workers and fire-fighters by making them more aware of their dangerous surrounding. Also next-generation of cloud-based, crowd-sourced, large-area sensor networks for urban monitoring can protect our communities from terrorist attacks. The diversity of potential industrial, environmental, and safety monitoring applications ensures sustainable growth paths in various domestic and international gas detection markets. The scientific component of this project will enhance the understanding of the complex processes occurring at the surfaces of these novel multicomponent nanoclusters, which could have profound impact in various other fields including photovoltaic, energy storage, and catalytic pollution-remediation.

This Small Business Innovation Research (SBIR) Phase I project will demonstrate single-chip ammonia (NH3) and carbon monoxide (CO) sensors using patent-pending innovation in multicomponent photocatalytic nanocluster-based hybrid sensor technology. Both NH3 and CO are toxic industrial chemicals with very serious health hazards, and often present in various industrial, farming, agricultural, and transportation related activities. High-performance mobile devices used in various operational situations represent a powerful infrastructure which could be leveraged for chemical monitoring. Due to their size and power requirement, traditional sensors are not suitable for mobile-platform deployment. Single-chip, ultra low-power selective detection of NH3 and CO will be a significant accomplishment towards the goal of development of mobile devices based multithreat monitors that can be used by industrial workers, civilians, first-responders, and soldiers for both personal safety and infrastructural security.


Grant
Agency: Environmental Protection Agency | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 99.19K | Year: 2014

Measuring individual exposure in real-time can revolutionize air quality monitoring in communities everywhere. Such information would allow citizens to take preventive measures to reduce their exposures to air toxics, which would impact their health and quality of life tremendously. Mobile devices such as smart-phones and tablets represent a powerful infrastructure that could be leveraged to develop personal air monitors. However, traditional sensor technologies (e.g., electrochemical and photo-ionization detectors) commonly used for industrial safety monitoring, are big, power-hungry, and have limited sensitivity and lifetime.N5 Sensors, Inc. will demonstrate highly-selective sensor architecture, utilizing nanoengineered gallium nitride (GaN) photoconductors functionalized with multicomponent nanoclusters of metal-oxides and metals. Innovation in photoenabled sensing enables these sensors to operate at room-temperature, resulting in a significant reduction in operating power. The strength of N5 Sensors’ technology is that it uses all standard microfabrication techniques, which promises economical, multianalyte, single-chip sensor solution. Due to the use of inert wide-bandgap semiconductor, metal-oxides and noble metals, the environmental impact of the sensors during their life cycles is minimal. By combining the “designer'” adsorption properties of multicomponent nanoclusters together with sensitive transduction capability of nanostructured GaN backbones, N5 Sensors will demonstrate sensors for benzene, toluene, ethylbenzene, xylene—commonly referred to as BTEX. Feasibility of this approach will be demonstrated by designing sensors and testing their sensitivity to such chemicals with detection range from 500 ppt to 1 percent, with minimal cross-sensitivity to various components of environmental matrix, namely particulate matter, reactive gases and non-target gases. Sub-micron structures will be formed on GaN epitaxial thin-films on sapphire using lithography and plasma etching. Such structures will be functionalized with multicomponent nanoclusters of metal­oxides and metals using reactive-sputter deposition. The Phase 1 effort will demonstrate BTEX sensors, consuming<1 mW of power and through detailed testing establish their operation reliability, measurement accuracy and calibration needs. Innovative sensor designs and measurement protocols will be evaluated for increased reliability and accuracy. Completion of Phase 2 will result in an array of nanoengineered sensors on a single chip, each tailored to sense specific air toxics: BTEX, Ox, SOx, CO2, and O3.Future prospects of such low-power, small form-factor sensors include embedded-chip or plug-in module with multi­analyte sensor arrays for the smart phones for citizens and soldiers for acquiring real-time environmental information. An opportunity for commercialization is in low-cost, mobile devices-based trace air toxic monitors for rapid alert in indoor and outdoor environments.

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