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A comprehensive quantitative root cause study of defect evolution leading to memory window closure from a charge balance and charge trapping perspective throughout all phases of a Si channel Hf0.5Zr0.5O2 (HZO) ferroelectric field-effect-transistor (FEFET) is reported. Starting with the first write pulse, an excessive SiO2 interlayer field is revealed that triggers the creation of defect levels Dit in excess of 1015 cm−2 eV−1 at the HZO–SiO2 interface screening ferroelectric (FE) polarization while enabling FE switching. Under subsequent early bipolar fatigue cycling (up to 104 cycles), defect creation commences at the SiO2–Si interface due to the high injected hole fluence (0.39 C/m2) during each stress pulse causing negative bias instability (NBI), which shifts the threshold voltage of the erase state VT,ERS by −0.3 V with accrual of permanently captured charge Nit of up to +5 × 10−3 C/m2 (3 × 1012 cm−2). Subsequently, Nit NBI generation at the SiO2–Si interface accelerates reaching levels of +7 × 10−2 C/m2, locking both FEFET program and erase drain current vs gate–source-voltage (ID–VGS) characteristics in the FEFET on-state inducing memory window closure at 105 cycles while FE switching (switched polarization Psw = 0.34 C/m2) remains essentially intact. These findings guide the down-selection toward suitable semiconductor/FE systems for charge balanced, reliable, and high endurance FEFETs. [ABSTRACT FROM AUTHOR]

Anisotropic growth of two-dimensional (2D) tungsten disulfide (WS2) crystals occurs during atomic layer deposition (ALD) from WS2 seeds at predetermined locations on large area dielectric substrates. The number of ALD reaction cycles determines the lateral dimensions of the WS2 crystals. This 2D synthesis approach is compatible with temperature sensitive structures due to the low deposition temperature and can be extended to other 2D materials and heterostructures thereof. The crystallinity of the seed and the selectivity of ALD precursors toward seeds and underlying starting surface affect the structural quality of the 2D crystals. [ABSTRACT FROM AUTHOR]

In the context of neuromorphic computation, spintronic memristors are investigated for their use as synaptic weights. In this paper, we propose and experimentally demonstrate a resistive synaptic device based on ten magnetic tunnel junctions (MTJs) connected in a serial configuration. Our device exhibits multiple resistance levels that support its use as a synaptic element. It allows for two operating knobs: external magnetic field and voltage pulses (Spin-Transfer Torque). Moreover, it can be operated in different ways. When varying continuously the amplitude of the voltage pulse and/or the magnetic field, eleven resistance states can be reached. In contrast, if the initial state of the chain is reset between every step, a very large number of levels are reached. Ideally, a total of 2 N resistance levels could be accessible. This coincides well with the desired analog-like behavior in ideal memristors. Since this device consists of a scalable number of N MTJs, and MTJ technology is continuously optimized and improved, the proposed memristor shows promise as a scalable synapse solution for neuromorphic hardware implementations. [ABSTRACT FROM AUTHOR]

The functionality of a cross-shaped Spin Torque Majority Gate (STMG) is primarily limited by the pinning of a domain wall (DW) at the center of the device. Here, an analytical model is built to calculate the conditions for such a pinning and to deduce the operating range. The assumptions of the model and the conclusions are validated by micromagnetic simulations. The total magnetic energy of the DW state is derived. By minimizing this energy with respect to two degrees of freedom, the DW stability condition is obtained. We find that the lateral length of the STMG is the critical dimension: it must be smaller than about five times the DW width. This result is confirmed by micromagnetic simulations with a high accuracy. In process, we solved a more fundamental problem: the macrospin limit of a finite ferromagnet containing one pinning site. We found the correction of the usual DW width expression due to finite length of wires. [ABSTRACT FROM AUTHOR]

Perpendicular Magnetic Anisotropy (PMA) is a key requirement for state of the art Magnetic Random Access Memories (MRAM). Currently, PMA has been widely reported in standard Magnetic Tunnel Junction material stacks using MgO as a dielectric. In this contribution, we present the first report of PMA at the interface with a high-j dielectric grown by Atomic Layer Deposition, HfO2. The PMA appears after annealing a HfO2\Co\Pt\Ru stack in N2 with the Keff of 0.25 mJ/m² as determined by Vibrating Sample Magnetometry. X-Ray Diffraction and Transmission Electron Microscopy show that the appearance of PMA coincides with interdiffusion and the epitaxial ordering of the Co\Pt bilayer. High-κ dielectrics are especially interesting for Voltage Control of Magnetic Anisotropy applications and are of potential interest for low-power MRAM and spintronics technologies. [ABSTRACT FROM AUTHOR]

Perpendicular Magnetic Anisotropy (PMA) is a key requirement for state of the art Magnetic Random Access Memories (MRAM). Currently, PMA has been widely reported in standard Magnetic Tunnel Junction material stacks using MgO as a dielectric. In this contribution, we present the first report of PMA at the interface with a high-j dielectric grown by Atomic Layer Deposition, HfO2. The PMA appears after annealing a HfO2\Co\Pt\Ru stack in N2 with the Keff of 0.25 mJ/m² as determined by Vibrating Sample Magnetometry. X-Ray Diffraction and Transmission Electron Microscopy show that the appearance of PMA coincides with interdiffusion and the epitaxial ordering of the Co\Pt bilayer. High-κ dielectrics are especially interesting for Voltage Control of Magnetic Anisotropy applications and are of potential interest for low-power MRAM and spintronics technologies. [ABSTRACT FROM AUTHOR]