{"project":{"acronym":"","projectId":11526,"title":"Integrating Two-Dimensional Nanomaterials and Molecular Dielectrics for Radiation-Hard Non-Volatile Memory","primaryTaxonomyNodes":[{"taxonomyNodeId":10568,"taxonomyRootId":8816,"parentNodeId":10567,"level":3,"code":"TX02.1.1","title":"Radiation Hardened Extreme Environment Components and Implementations","definition":"Radiation Hardened (rad-hard) components are technologies tolerant to radiation and/or extreme temperatures. These technologies allow for miniaturization and increased ruggedness of spacecraft electronics for enhancing flexibility in vehicle configuration and design. This area also includes technologies for fabricating electronic components for space environments, rad-hard-by-design implementation techniques, and implementations developed to deal with extreme temperatures environments that would obviate the need for thermal management systems.","exampleTechnologies":"Radiation mitigation techniques, rad-hard/tolerant Graphical Processor Unit (GPU) & Display elements, Rad-hard/tolerant data processing, rad-hard/tolerant general purpose flight processor, rad-hard/tolerant high-capacity memory, nanoelectronics based memory devices, two-dimensional (High-capacity Memory, Nano electronics Based Memory Devices, 2D nanomaterials based electronics, components with on-chip thermal control capability, advanced passive technologies (e.g. super capacitors)","hasChildren":false,"hasInteriorContent":true}],"startTrl":2,"currentTrl":3,"endTrl":3,"benefits":"As long-term TID effects are the primary concern in a FG flash memory cell, the incorporation of graphene, MoS(2), and SANDs into a FG flash memory device holds promise for a radiation-hard nonvolatile memory.","description":"The space radiation environment presents a significant hazard to the critical electronic components used in a variety of space applications. Many such applications require data storage solutions that provide high storage capacities while abiding strict power consumption limitations. Specifically, the need for radiation-hard non-volatile memories is a long-standing problem in the space community. The proposed work describes a progression toward a radiation-hard, high performance non-volatile memory device by implementing principles from terrestrial memory technology using two-dimensional nanomaterials with proven radiation hardness. Graphene, consisting of a single-atom thick hexagonal carbon lattice, has been shown to exhibit a number of superlative qualities as a nanoelectronic material for many applications. Perhaps most relevantly, graphene has recently been incorporated as the floating gate (FG) layer of a flash memory cell, resulting in improved device performance. Single layer MoS(2) is a three-atom thick material that shares many of the desirable electronic qualities of graphene. In addition, MoS(2) thin-film transistors (TFTs) have demonstrated superior switching capability compared to graphene. These qualities make MoS(2) an exceptional candidate as a channel material for a FG flash memory device. Finally, self-assembled nanodielectrics (SANDs) are a unique class of hybrid organic/inorganic dielectric thin films that boast low leakage current and high dielectric constant. The integration of SANDs with graphene and many other low dimensional nanomaterials has demonstrated improved TFT device performance compared to traditional gate dielectric materials. Initial tests suggest SANDs are hard to ionizing radiation, and the total ionizing dose (TID) response of graphene has been studied, resulting in strong evidence that graphene is TID-hard as well. By analogy to the two-dimensional structure of graphene, MoS(2) is likely to be TID-hard as well. As long-term TID effects are the primary concern in a FG flash memory cell, the incorporation of graphene, MoS(2), and SANDs into a FG flash memory device holds promise for a radiation-hard nonvolatile memory. This integration will require that that SANDs be deposited atop graphene and MoS(2). Existing variants of SANDs are presently deposited only on SiO(2) terminated surfaces, limiting thin-film transistor devices to those having a global back gate geometry on a Si wafer. Moreover, deposition of ultrathin oxide materials on graphene (and possibly MoS(2)) has historically proven problematic, as its surface chemistry impedes the deposition of uniform, high quality dielectric films. Recently, the Hersam Laboratory has developed a fabrication scheme that uses a self-assembled organic seeding layer to facilitate the deposition of ultrathin, conformal oxide materials on graphene via atomic layer deposition (ALD). The extension of this scheme to the vapor deposition of SANDs on graphene and MoS(2) represents a significant challenge that will necessitate the development of a new SAND material and deposition process that is compatible with ALD. Overall, the proposed device structure motivates the following research objectives: Development of a novel SAND variant that is compatible with atomic layer deposition. Integration of SAND on graphene by deposition on organic self-assembled monolayers. Integration of SAND on MoS2 by deposition on organic self-assembled monolayers. Complete assembly and testing of MoS(2)/SAND/graphene FG flash memory device.","startYear":2012,"startMonth":9,"endYear":2016,"endMonth":8,"statusDescription":"Completed","principalInvestigators":[{"contactId":311964,"canUserEdit":false,"firstName":"Mark","lastName":"Hersam","fullName":"Mark Hersam","fullNameInverted":"Hersam, Mark","primaryEmail":"m-hersam@northwestern.edu","publicEmail":false,"nacontact":false}],"programDirectors":[{"contactId":84634,"canUserEdit":false,"firstName":"Claudia","lastName":"Meyer","fullName":"Claudia M Meyer","fullNameInverted":"Meyer, Claudia M","middleInitial":"M","primaryEmail":"claudia.m.meyer@nasa.gov","publicEmail":true,"nacontact":false}],"programExecutives":[{"contactId":84634,"canUserEdit":false,"firstName":"Claudia","lastName":"Meyer","fullName":"Claudia M Meyer","fullNameInverted":"Meyer, Claudia M","middleInitial":"M","primaryEmail":"claudia.m.meyer@nasa.gov","publicEmail":true,"nacontact":false}],"programManagers":[{"contactId":183514,"canUserEdit":false,"firstName":"Hung","lastName":"Nguyen","fullName":"Hung D Nguyen","fullNameInverted":"Nguyen, Hung D","middleInitial":"D","primaryEmail":"hung.d.nguyen@nasa.gov","publicEmail":true,"nacontact":false}],"projectManagers":[{"contactId":302562,"canUserEdit":false,"firstName":"Mahmooda","lastName":"Sultana","fullName":"Mahmooda Sultana","fullNameInverted":"Sultana, Mahmooda","primaryEmail":"mahmooda.sultana@nasa.gov","publicEmail":true,"nacontact":false}],"coInvestigators":[{"contactId":254412,"canUserEdit":false,"firstName":"Julian","lastName":"Mcmorrow","fullName":"Julian Mcmorrow","fullNameInverted":"Mcmorrow, Julian","primaryEmail":"julian.mcmorrow@nasa.gov","publicEmail":true,"nacontact":false}],"website":"https://www.nasa.gov/directorates/spacetech/home/index.html","libraryItems":[{"caption":"Project Image Integrating Two-Dimensional Nanomaterials and Molecular Dielectrics for Radiation-Hard Non-Volatile Memory","file":{"fileExtension":"jpg","fileId":313965,"fileName":"11526-1363186802902","fileSize":194342,"objectId":306548,"objectType":{"lkuCodeId":889,"code":"LIBRARY_ITEMS","description":"Library Items","lkuCodeTypeId":182,"lkuCodeType":{"codeType":"OBJECT_TYPE","description":"Object Type"}},"objectTypeId":889,"fileSizeString":"189.8 KB"},"files":[{"fileExtension":"jpg","fileId":313965,"fileName":"11526-1363186802902","fileSize":194342,"objectId":306548,"objectType":{"lkuCodeId":889,"code":"LIBRARY_ITEMS","description":"Library Items","lkuCodeTypeId":182,"lkuCodeType":{"codeType":"OBJECT_TYPE","description":"Object Type"}},"objectTypeId":889,"fileSizeString":"189.8 KB"}],"id":306548,"title":"11526-1363186802902.jpg","description":"Project Image Integrating Two-Dimensional Nanomaterials and Molecular Dielectrics for Radiation-Hard Non-Volatile Memory","libraryItemTypeId":1095,"projectId":11526,"primary":true,"publishedDateString":"","contentType":{"lkuCodeId":1095,"code":"IMAGE","description":"Image","lkuCodeTypeId":341,"lkuCodeType":{"codeType":"LIBRARY_ITEM_TYPE","description":"Library Item Type"}}}],"transitions":[{"transitionId":75597,"projectId":11526,"transitionDate":"2016-08-01","path":"Closed Out","details":"The coupling of hybrid organic-inorganic gate dielectrics with emergent unconventional semiconductors has yielded transistor devices exhibiting record-setting transport properties. However, extensive electronic transport measurements on these high-capacitance systems are often convoluted with the electronic response of the semiconducting silicon substrate. In my first publication, we demonstrate the growth of solution-processed zirconia self-assembled nanodielectrics (Zr-SAND) on template-stripped aluminum substrates. The resulting Zr-SAND on Al structures leverage the ultrasmooth (r.m.s. roughness < 4 Å), chemically uniform nature of template-stripped metal substrates to demonstrate the same exceptional electronic uniformity (capacitance ~ 700 nF cm-2, leakage current < 1 A cm-2 at -2 MV cm-1) and multilayer growth of Zr-SAND on Si, while exhibiting superior temperature and voltage capacitance responses. These results are important to conduct detailed transport measurements in emergent transistor technologies featuring SAND as well as for future applications in integrated circuits or flexible electronics. Atomically thin MoS2 has generated tremendous interest as a nanomaterial for emerging electronic applications. Its low-dimensional nature and potential for low-power electronics are particularly appealing for space-bound electronics, motivating the need to develop a fundamental understanding of the response of MoS2-based electronic devices to the space radiation environment. In my second publication, we gauge the response of MoS2 field-effect transistors (FETs) to vacuum ultraviolet (VUV) total ionizing dose (TID) radiation. Single-layer (SL) and multilayer (ML) MoS2 FETs are compared to identify differences that arise from thickness and band structure variations. Computations from the evolution of the FET transport properties are leveraged to identify the nature of the VUV-induced trapped charge, isolating the effects of interface and bulk oxide trapped charge. In both the SL and ML cases, oxide trapped holes compete with interface trapped electrons, exhibiting an overall shift toward negative gate bias. Raman spectroscopy identifies no variation as a result of VUV exposure, eliminating crystalline damage or oxidation as a possible mechanism that contributes to the MoS2 FET evolution. Overall, because the charge trapping behavior in this MoS2 electronic system is consistent with that observed in conventional electronic systems, this work presents avenues for achieving radiation hardness in future MoS2-based electronic devices. With the growing adoption of interconnected electronic devices in consumer and industrial applications, there is increasing demand for robust security protocols in connected devices to securely transmit and receive sensitive data. Hardware true random number generators (TRNGs), commonly used to create encryption keys, offer significant advantages over software pseudo-random number generators. However, future portable networked devices will require small, low cost, flexible TRNGs with low computational complexity. These rigorous constraints position single-walled carbon nanotubes (SWCNTs) as the ideal candidates for the semiconducting components in next-generation security devices. In my third publication, we demonstrate the first solution-processed TRNG using SWCNT static random access memory (SRAM) cells that digitize thermal noise to generate random bits. We design a bit generation strategy that can be readily implemented in hardware with minimal transistor and computational overhead, and the quality of our generated output is confirmed using standardized statistical tests. By using solution-processed semiconducting SWCNT networks as the semiconducting channel and CMOS compatible fabrication, we demonstrate a promising approach to low-cost, ultra-thin, and flexible security devices. These increasingly complex demonstrations of single-walled carbon nanotube-based (SWCNT) integrated circuit elements mark the maturation of the technology for use in next-generation electronics devices. In addition to the SRAM work described above, organic materials have been leveraged as dopant and encapsulation layers to enable stable SWCNT-based rail-to-rail, low power complementary metal-oxide-semiconductor (CMOS) circuit elements. As SWCNT-CMOS is adopted in emerging technologies, its suitability for use in next-generation space applications must be assessed. In my fourth publication, we study total ionizing dose (TID) effects in enhancement-mode SWCNT-CMOS inverters having the same organic doping and encapsulation layers utilized in the TRNG work. Details of the evolution of the device transport properties are revealed by in situ and in operando measurements, identifying the n-type device as the more TID-sensitive component of the CMOS system by revealing over an order of magnitude larger degradation of the static power dissipation. Radiation-hardening approaches are explored, and the SWNCT-CMOS technology is found to be TID-hard under dynamic bias operation. The incorporation of organic materials as dopants presents a unique system for the study of space radiation effects while the CMOS integration allows the study of system-level effects previously unobservable in SWCNT devices.","infoText":"Closed out","infoTextExtra":"","dateText":"August 2016"}],"primaryImage":{"file":{"fileExtension":"jpg","fileId":313965,"fileSizeString":"0 Byte"},"id":306548,"description":"Project Image Integrating Two-Dimensional Nanomaterials and Molecular Dielectrics for Radiation-Hard Non-Volatile Memory","projectId":11526,"publishedDateString":""},"responsibleMd":{"acronym":"STMD","canUserEdit":false,"city":"","external":false,"linkCount":0,"organizationId":4875,"organizationName":"Space Technology Mission Directorate","organizationType":"NASA_Mission_Directorate","naorganization":false,"organizationTypePretty":"NASA Mission Directorate"},"program":{"acronym":"STRG","active":true,"description":"
\tThe Space Technology Research Grants Program will accelerate the development of "push" technologies to support the future space science and exploration needs of NASA, other government agencies and the commercial space sector. Innovative efforts with high risk and high payoff will be encouraged. The program is composed of two competitively awarded components.
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