DEFECT ENGINEERING OF PHASE CHANGE MATERIALS FOR ULTRA-LOW POWER DEVICES
Abstract
STATEMENT OF WORKYear 1:1) Growth and characterization of PCM nanowires (NWs) of different controlled compositions and size.2) Electrical characterization of pristine PCM NWs of varying compositions.3) Detailed study of different types of ion radiation (He+, Ar+ etc) as a function ofacceleration voltage and exposure time on their structural properties. Advance existingwork on GeTe and then extend to Ge-Sb-Te alloys.4) Electron microscopy characterization of ion radiated PCM NWs of different compositionand ion dosage. Map of composition-dosage-structure properties.Year 2 (Option):1) Basic electrical characterization of Ge-Sb-Te alloy NWs as a function of composition andion dosage.2) Switching characteristics of Ge-Sb-Te NW alloys as a function of composition and iondosage.3) Characterization of switching current densities as a function of composition and iondosage and NW dimensions.4) Complete characterization of switching characteristics leading to a map of composition dosage-switching properties.5) Obtain optimization parameters for lowest power density switching devices.Year 3 (Option):1) Transport properties of G-Sb-Te NWs as a function of dosage (structure) and electronlocalization regimes. Effect of electron-phonon coupling on switching characteristics.2) Detailed device characteristics such as endurance, cyclability and resistance and thresholdvoltage drift as a function of composition and ion dosage. Obtain optimized parameters.3) Evaluate if optical switching is also affected by ion dosage leading to lowering of opticalpower density for switching.4) Verify the concept on polycrystalline thin-film devices.OBJECTIVEThe objective of this proposal is to utilize the unique aspects of phase-change alloys to devise crystal-amorphous pathways without going through the energy consuming liquid melt process. This will enable ultra-low-power electronic and photonic devices that utilize the changes in resistivity and refractive index associated with phase-change materials (PCMs).APPROACHBased on recent breakthroughs in the PI~s lab, the team at UPenn will explore the subtle defect-based pathways which lead to large lattice distortions in phase-change alloys owing to their unique bonding hierarchy that can lead to a collapse of the long-range crystal order leading to amorphization. Then, they will pre-engineer defects/lattice distortions in the material using high-energy ion bombardment, so that once precisely engineered, a very small energy impulse can amorphize the material leading to energy- efficient operations and longer device endurance due to the small amount of heat produced in the system that otherwise leads to material degradation. They will also determine if these strategies can potentially mitigate the problem of electromigration, a common device failure mechanism associated with large switching current densities in PCMs.MERIT / RELEVANCEA goal of this work is to produce engineered phase-change chalcogenides that will achieve phase switching with three to four orders of magnitude lower current density. This could enable a variety of applications including RF electronics, memory storage, arithmetic processing, optical memory, and optical/electronic mixed-mode operation, all with ultra-low power capabilities. The basic research and potential applications are relevant to the ONR Electromagnetic Materials Program and the Electromagnetic Maneuver Warfare CNR priority. Prof. Agarwal has established a strong group in the Materials Science and Engineering Department at the University of Pennsylvania. This group made important advances in nanoscale photonic, electronic and energy conversion devices and systems over the past several years. This innovative proposal builds on their recent publications in Science (2012) and Nano Letters (2014) in which they made breakthroughs in the understanding of phase-change mechanisms. The next logical step, as outlined in the proposal, is to use that understanding to engineer phase changes with
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 08, 2016
- Source ID
- N000141612350
Entities
People
- Ritesh Agarwal
Organizations
- Office of Naval Research
- United States Navy
- University of Pennsylvania