The exponential growth in digital data requires storage technologies with ever increasing bit densities at reduced costs. In this paper, we demonstrate the feasibility of a novel memory concept where information is stored in the form of thickness-modulated electrochemically deposited metal multilayers. Specifically, using a citrate-based Cu-Ni plating bath and memory holes approaching technologically relevant dimensions (80 nm diameter, 1 mu m depth), we show that data stored as modulated Ni|Cu stacks can be controllably written and retrieved. The results shown in this paper would directly translate to a bit density of 1 Gbit/mm2, on par with what hard disk drives achieve today. We further discuss the path to achieve 1 Tbit/mm2 and evaluate other performance characteristics in view of the requirements for secondary storage applications.

Flowing an electrical current that is both of high areal density and large spin polarization across a magnetic tunnel junction (MTJ) can, through spin-transfer torque (STT), alter the relative magnetic orientation of the MTJ’s ferromagnetic electrodes. This effect has enabled key next-generation MTJ applications and commercialized products, from memories to artificial synapses and energy harvesters. As MTJs are now downscaled to 2 nm, basic experimental data challenge the accepted understanding of their operation. From transport spectroscopy, ferromagnetic resonance experiments and ab-initio calculations it is revealed that the high conductivity of STT-ready MTJs, and the STT effect therein, is mediated by oxygen vacancy complexes within the MgO barrier. Our work positions the oxygen vacancy at the core of MgO spintronics. This should disrupt the status-quo on STT-MRAM R&D, by generating defect-specific research and new ideas to confer additional functionality to these next-generation electronic devices, as a nanoelectronics platform to industrialize quantum physics.

Materials and interfacial engineering yielded ferroelec-tricity in Al1-xScxN films of 15 nm thickness for the first time. Bottom electrodes were explored and selected for optimal properties through modification of the strain state and thus the texture in the films. Pt bottom interfaces were shown to be the best for the widest doping window of Sc in the structure and the lowest leakage. Mo bottom interfaces promoted mixed texture in the films, which led to a reduced breakdown E-field and a reduced doping window. Top electrode stacks were shown to modify strain state and effect leakage, enabling full interfacial engineering of this material. Here, Mo top electrode interfaces caused a reduction of the coercive electric field, thus allowing strain engineering of this material and opening the door to application in memory devices.

Energy-efficient memory elements having a non-volatile memory window (MW) with a non-destructive read operation are highly desirable for both random access memory and compute-in-memory applications. In this work, we demonstrate a record high non-volatile capacitive MW and non-destructive read in hafnium zirconate-based metal-ferroelectric-metal capacitors (FeCAPs). Firstly, we show that a non-zero capacitive MW at zero read voltage can be realized by engineering an asymmetry between the top and bottom ferroelectric-metal interfaces and demonstrate a record high MW of $\sim {4.71}\times \epsilon _{{0}}$ at 0 V. Secondly, we show that the capacitive MW can be further improved by optimizing a non-zero read voltage. This allows to achieve a record high MW of $\sim {7.5}\times \epsilon _{{0}}$ for the asymmetric FeCAP, and even opens up a MW as high as $\sim {8.0}\times \epsilon _{{0}}$ for the symmetric FeCAP. Finally, we demonstrate that the MW can be reliably read non-destructively as long as the read voltage is carefully selected to avoid partial or full polarization switching during the read operation.

We fabricated and characterized IGZO-channel back-gated FeFET. It has been found that a Memory Window (MW) reading scheme based on reverse $I_{d}-V_{g}$ sweep can strongly attenuate the significant read disturb which affects the low- V t state. This instability of low- $\mathrm{V}_{\mathrm{t}}$ state origins from the asymmetric PV loop and small negative coercive voltage. With this optimized reading scheme, we proved that interfacial engineering, by inserting a $\mathrm{NbO}_{\mathrm{x}}$ layer between La HZO and IGZO, can significantly improve $2 P_{r}$, MW (to $0.7 \mathrm{~V}$), and endurance (to 10 7 cycles). This makes the $\mathrm{La}: \mathrm{HZO} / \mathrm{NbO}_{\mathrm{x}} / \mathrm{IGZO}$ FeFET a promising structure for high-endurance and low-latency NVM.

Thin films based on stoichiometric hafnium zirconate doped and co-doped with La, Gd, and/or Y have been grown by atomic layer deposition on TiN electrodes. The resulting TiN-ferroelectric-TiN capacitors have shown high endurance up to 1 x 10(11) switching cycles. The simultaneous use of two dopants (Y, La) or (Gd, La) in hafnium zirconate increases the amount of orthorhombic and tetragonal phases. Fatigue-free capacitors with remnant polarization >= 15 mu C/cm(2) at 1 x 10(11) endurance cycles have been obtained for dopants having an atomic fraction of about 1.2-1.8% and showing great promise as active materials for emerging memory applications.

A 25 nm pitch 3D-NAND gate-all-around macaroni device with 10 nm gate length, is structurally and electrically demonstrated for the first time. The key fabrication process steps enabling the scaled devices are discussed, such as TiN metal fill and Al2O3 deposition inside the memory hole. We show that an appropriate biasing scheme can reduce the detrimental impact of neighbor-induced barrier lowering on both the transistor characteristics and the memory operation, achieving a −4 V VT and STS of 0.3 V/dec and a memory window of 7 V. Reliability is not significantly impacted at scaled pitches. This study provides a basis for fabrication and understanding of future ultra-high bit density 3D-NAND memories.

The quantum states of nano-objects can drive electrical transport properties across lateral and local-probe junctions. This raises the prospect, in a solid-state device, of electrically encoding information at the quantum level using spin-flip excitations between electron spins. However, this electronic state has no defined magnetic orientation and is short-lived. Using a novel vertical nanojunction process, these limitations are overcome and this steady-state capability is experimentally demonstrated in solid-state spintronic devices. The excited quantum state of a spin chain formed by Co phthalocyanine molecules coupled to a ferromagnetic electrode constitutes a distinct magnetic unit endowed with a coercive field. This generates a specific steady-state magnetoresistance trace that is tied to the spin-flip conductance channel, and is opposite in sign to the ground state magnetoresistance term, as expected from spin excitation transition rules. The experimental 5.9 meV thermal energy barrier between the ground and excited spin states is confirmed by density functional theory, in line with macrospin phenomenological modeling of magnetotransport results. This low-voltage control over a spin chain's quantum state and spintronic contribution lay a path for transmitting spin wave-encoded information across molecular layers in devices. It should also stimulate quantum prospects for the antiferromagnetic spintronics and oxides electronics communities.

In this paper, the kinetics of Ni metal induced lateral crystallization (MILC) in a Si channel has been thoroughly investigated. The impact of excess Ni supply, high-and-long thermal treatments, and fast ramp rate annealing on the quality of Si channel formed are reported. We show that it is possible to achieve up to 10 times higher mobility, and enhanced channel control with a controlled MILC process compared to a regular polysilicon channel.

We demonstrate the integration of Ruthenium (Ru) and Molybdenum (Mo) as Word Line (WL) metals in a record 40nm pitch 3D-NAND device through an optimized Replacement Metal Gate (RMG) process. The optimized RMG process minimizes oxide regrowth which affects WL fill capability in reduced pitches. Ru and Mo gates show better resistivity (ρ) and memory characteristics compared to the currently used Tungsten WL. We demonstrate good channel control and program/erase (P/E) characteristics down to 20nm WL. Best P/E is obtained for Mo with 2nm HfOx liner after a post metallization anneal (PMA) at 750°C for 20mins, while devices with Ru WL show better retention.

Electrically manipulating the quantum properties of nano-objects, such as atoms or molecules, is typically done using scanning tunnelling microscopes and lateral junctions. The resulting nanotransport path is well established in these model devices. Societal applications require transposing this knowledge to nano-objects embedded within vertical solid-state junctions, which can advantageously harness spintronics to address these quantum properties thanks to ferromagnetic electrodes and high-quality interfaces. The challenge here is to ascertain the device's effective, buried nanotransport path, and to electrically involve these nano-objects in this path by shrinking the device area from the macro- to the nano-scale while maintaining high structural/chemical quality across the heterostructure. We've developed a low-tech, resist- and solvent-free technological process that can craft nanopillar devices from entire in-situ grown heterostructures, and use it to study magnetotransport between two Fe and Co ferromagnetic electrodes across a functional magnetic CoPc molecular layer. We observe how spin-flip transport across CoPc molecular spin chains promotes a specific magnetoresistance effect, and alters the nanojunction's magnetism through spintronic anisotropy. In the process, we identify three magnetic units along the effective nanotransport path thanks to a macrospin model of magnetotransport. Our work elegantly connects the until now loosely associated concepts of spin-flip spectroscopy, magnetic exchange bias and magnetotransport due to molecular spin chains, within a solid-state device. We notably measure a 5.9meV energy threshold for magnetic decoupling between the Fe layer's buried atoms and those in contact with the CoPc layer forming the so-called 'spinterface'. This provides a first insight into the experimental energetics of this promising low-power information encoding unit.

On-going research is exploring novel energy concepts ranging from classical to quantum thermodynamics. Ferromagnets carry substantial built-in energy due to ordered electron spins. Here, we propose to generate electrical power at room temperature by utilizing this magnetic energy to harvest thermal fluctuations on paramagnetic centers using spintronics. Our spin engine rectifies current fluctuations across the paramagnetic centers’ spin states by utilizing so-called ‘spinterfaces’ with high spin polarization. Analytical and ab-initio theories suggest that experimental data at room temperature from a single MgO magnetic tunnel junction (MTJ) be linked to this spin engine. Device downscaling, other spintronic solutions to select a transport spin channel, and dual oxide/organic materials tracks to introduce paramagnetic centers into the tunnel barrier, widen opportunities for routine device reproduction. At present MgO MTJ densities in next-generation memories, this spin engine could lead to ‘always-on’ areal power densities that are highly competitive relative to other energy harvesting strategies.

The field of tunnelling spintronics has flourished through the study of magnetic tunnel junctions (MTJs) with MgO barriers. The combination of high spintronic performance and low effective barrier heights has enabled new technologies, ranging from next-generation memories to bio-inspired computing. This combination is made possible by structural defects such as oxygen vacancies. So far, experiments have pegged an energy separation between these localized states and the Fermi level, while theory has predicted that these are in fact occupied states. To rationalize the defect-mediated potential tunnelling landscape, we have performed experiments in which we tune the MTJ's Fermi level by altering one electrode's work function. We find that switching the top electrode from FeCoB to FeB increases the amplitude of defect-mediated barrier heights. Ab initio theory attributes this increase to an increased energy separation between the localized states of single and double oxygen vacancies and the Fermi level. We thus extract a rationalized potential landscape of tunnelling across oxygen vacancies in MgO involving occupied states. In junctions with high R.A. product such as ours, this leads to a picture of hole tunnelling.

One promising route toward encoding information is to utilize the two stable electronic states of a spin crossover molecule. Although this property is clearly manifested in transport across single molecule junctions, evidence linking charge transport across a solid-state device to the molecular film's spin state has thus far remained indirect. To establish this link, we deploy materials-centric and device-centric operando experiments involving X-ray absorption spectroscopy. We find a correlation between the temperature dependencies of the junction resistance and the Fe spin state within the device's [Fe(H2B(pz)2)2(NH2-phen)] molecular film. We also factually observe that the Fe molecular site mediates charge transport. Our dual operando studies reveal that transport involves a subset of molecules within an electronically heterogeneous spin crossover film. Our work confers an insight that substantially improves the state-of-the-art regarding spin crossover-based devices, thanks to a methodology that can benefit device studies of other next-generation molecular compounds.

The quantum mechanical tunnelling process conserves the quantum properties of the particle considered. As applied to solid-state tunnelling (SST), this physical law was verified, within the field of spintronics, regarding the electron spin in early experiments across Ge tunnel barriers, and in the 90s across Al2O3 barriers. The conservation of the quantum parameter of orbital occupancy, as grouped into electronic symmetries, was observed in the u002700s across MgO barriers, followed by SrTiO3 (STO). In the solid-state, an additional subtlety is the sign of the charge carrier: are holes or electrons involved in transport? We demonstrate that SST across MgO magnetic tunnel junctions (MTJs) involves holes by examining how shifting the MTJu0027s Fermi level alters the ensuing barrier heights defined by the barrieru0027s oxygen vacancies. In the process, we consolidate the description of tunnel barrier heights induced by specific oxygen-vacancy induced localized states. This should provide important insight into spin transfer torque physics across MgO.

The quantum mechanical tunnelling process conserves the quantum properties of the particle considered. As applied to solid-state tunnelling (SST), this physical law was verified, within the field of spintronics, regarding the electron spin in early experiments across Ge tunnel barriers, and in the 90s across Al2O3 barriers. The conservation of the quantum parameter of orbital occupancy, as grouped into electronic symmetries, was observed in the '00s across MgO barriers, followed by SrTiO3 (STO). Barrier defects, such as oxygen vacancies, partly conserve this electronic symmetry. In the solid-state, an additional subtlety is the sign of the charge carrier: are holes or electrons involved in transport? We demonstrate that SST across MgO magnetic tunnel junctions (MTJs) with a large resistance-area (RA) product involves holes by examining how shifting the MTJ's Fermi level alters the ensuing barrier heights defined by the barrier's oxygen vacancies. In the process, we consolidate the description of tunnel barrier heights induced by specific oxygen-vacancy induced localized states. Our work opens prospects to understand the concurrent observation of high TMR and spin transfer torque across MgO-based nanopillars.