Nanomaterial Registry

The Nanomaterials Registry is an ambitious and much needed resource for the nanotechnology community. This project is funded by the National Institute of Biomedical Imaging and Bioengineering (NIBIB), the National Institute of Environmental Health Sciences (NIEHS), and the National Cancer Institute (NCI) as a contract to RTI International to develop the Nanomaterials Registry. In this multi-year project, RTI is working to establish a web-based registry that will provide a public resource of curated information on the biological and environmental interactions of well-characterized nanomaterials. This registry, besides being an authoritative source, will provide additional information, including links to associated publications, modeling tools, computational results, and manufacturing guidance. Through this project, the team will also work to • Create and effectively facilitate an Advisory Board of domain experts that span stakeholder groups and technology expertise; • Develop an effective means to search, query and report on nanomaterial data and associated information by leveraging consensus-generated sets of Minimum Information About Nanomaterials (MIAN) and a logical nanomaterial ontology that spans broad biological and environmental implications; • Design and implement a curation process to organize and evaluate information into a web-accessible database that is user-friendly and engaging to nanomaterial users and the public alike; and • Maximize opportunities for public and professional participation and comment and to educate interested professionals and individuals on nanomaterial data relevant to biological and environmental implications through outreach and other communication activities. As a public resource, the registry is being designed to facilitate data validation and data quality improvement of nanomaterials by the research community; enhance the development of new models, assays, standards, and manufacturing methods; and accelerate the translation of new nanomaterials for biomedical and environmental applications. This activity will also specifically address such diverse activities as regulation, product development, and environmental remediation and will allow for the integration of diverse data sources in this field. Information exchange and data sharing is a critical component to this program, as the registry is being designed to leverage existing resources, communities, and databases already constructed and those under development. By providing an overview of the registry goals and objectives, additional opportunities for sharing can be identified early in this project

Aerosol process for fabricating discontinuous floating gate microelectronic devices

A process for forming an aerosol of semiconductor nanoparticles includes pyrolyzing a semiconductor material-containing gas then quenching the gas being pyrolyzed to control particle size and prevent uncontrolled coagulation. The aerosol is heated to densify the particles and form crystalline nanoparticles. In an exemplary embodiment, the crystalline particles are advantageously classified by size using a differential mobility analyzer and particles having diameters outside of a pre-selected range of sizes, are removed from the aerosol. In an exemplary embodiment, the crystalline, classified and densified nanoparticles are oxidized to form a continuous oxide shell over the semiconductor core of the particles. The cores include a density which approaches the bulk density of the pure material of which the cores are composed and the majority of the particle cores are single crystalline. The oxidized particles are deposited on a substrate using thermophoretic, electrophoretic, or other deposition means. The deposited particles form a stratum or discontinuous monolayer of oxidized semiconductor particles. In an exemplary embodiment, the stratum is characterized by a uniform particle density on the order of 10.sup.12 to 10.sup.13 particles/cm.sup.2 and a tightly controlled range of particle sizes. A plurality of adjacent particles contact each other, but the oxide shells provide electrical isolation between the particles of the stratum. Clean processing techniques provide a density of foreign atom contamination of less than 10.sup.11 atoms/cm.sup.2. The stratum is advantageously used as the floating gate in a non-volatile memory device such as a MOSFET. The non-volatile memory device exhibits excellent endurance behavior and long-term non-volatility

Aerosol silicon nanoparticles for use in semiconductor device fabrication

A stratum or discontinuous monolayer of dielectric-coated semiconductor particles includes a high density of semiconductor nanoparticles with a tightly controlled range of particle sizes in the nanometer range. In an exemplary embodiment, the nanoparticles of the stratum are substantially the same size and include cores which are crystalline, preferably single crystalline, and include a density which is approximately the same as the bulk density of the semiconductor material of which the particle cores are formed. In an exemplary embodiment, the cores and particles are preferably spherical in shape. The stratum is characterized by a uniform particle density on the order of 10.sup.12 to 10.sup.13 particles/cm.sup.2. A plurality of adjacent particles contact each other, but the dielectric shells provide electrical isolation and prevent lateral conduction between the particles of the stratum. The stratum includes a density of foreign atom contamination of less than 10.sup.11 atoms/cm.sup.2. The stratum is advantageously used as the floating gate in a non-volatile memory device such as a MOSFET. The non-volatile memory device including the discontinuous floating gate of semiconductor nanoparticles exhibits excellent endurance behavior and long-term non-volatility

Ultraclean Two-Stage Aerosol Reactor for Production of Oxide-Passivated Silicon Nanoparticles for Novel Memory Devices

Silicon nanoparticle-based floating gate metal oxide semiconductor field effect devices are attractive candidates for terabit cm^–2 density nonvolatile memory applications. We have designed an ultraclean two-stage aerosol process reactor and 200 mm wafer deposition chamber in order to integrate Si/SiO2 nanoparticles into memory devices. In the first stage, silicon nanoparticles are synthesized by thermal decomposition of silane gas in a reactor that has been optimized to produce nonagglomerated nanoparticles at rates sufficient for layer deposition. In the second stage, the silicon particles are passivated with thermal oxide that partly consumes the particle. This two-stage aerosol reactor has been integrated to a 200 mm silicon wafer deposition chamber that is contained within a class 100 cleanroom environment. This entire reactor system conforms to rigorous cleanliness specifications such that we can control transition metal contamination to as good as 10^10 atoms cm^–2. The deposition chamber has been designed to produce a controllable particle density profile along a 200 mm wafer where particles are thermophoretically deposited uniformly over three-quarters of the wafer. Thus, we now have the capability to deposit controlled densities of oxide-passivated silicon nanoparticles onto 200 mm silicon wafers for production of silicon nanoparticle memory devices

The feasibility of inert colloidal processing of silicon nanoparticles

Silicon nanoparticles have important applications, including nonvolatile floating-gate memory devices. To prevent device performance variations, particle size and oxide thicknesses need to be controlled with a high degree of precision. Additionally, producing well-ordered, two-dimensional arrays of nanoparticles may require the exploitation of self-assembly techniques and colloidal forces, which in turn requires that silicon nanoparticles first come into contact with liquids. Until recently, aerosol silicon nanoparticle collection into liquid was assumed to be an inert process. Once formed, the silicon nanoparticle colloid was assumed to be inert. In fact, silicon nanoparticles produced in the aerosol phase by dilute silane pyrolysis and size classified with a differential mobility analyzer undergo a size reduction upon collection in ethylene glycol, water, and ethanol. Unclassified polydisperse silicon aerosol nanoparticles with an average diameter of 11 nm become monodisperse when collected in a colloid and have a final particle diameter of 2–5 nm. Further evidence suggests that silicon nanoparticles collected in ethanol react with the ethanol to produce tetraalkylorthosilicate-like species. Collections of aerosol silicon nanoparticles in degassed water do not show measurable differences between the aerosol and colloidal size distributions. This reduced reactivity to the solvent indicates that the presence of dissolved oxygen in the solvent may be responsible for the reactivity between the silicon nanoparticles and the solvent