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The effects of high temperature on an asymmetrically doped vertical pillar-type metal-oxide-semiconductor field-effect transistor (MOSFET) were investigated. An asymmetrically doped source and drain (S/D) can be easily formed in a vertical pillar-type FET due to the unique pillar structure. When high temperature is applied to the asymmetric S/D of a vertical pillar-typed silicon nanowire, it affects mobility and carrier injection differently. It decreases mobility by phonon scattering for heavily doped S and intermediately doped D. In contrast, it enhances carrier injection for intermediately doped S and heavily doped D. Thus the ON-state current (ION) shows opposite dependencies at high temperature. This tendency was verified by electrical measurements and supporting simulations. [ABSTRACT FROM AUTHOR]

The single-transistor latch in vertical pillar-type FETs with asymmetric source and drain (S/D) was investigated for capacitorless one transistor dynamic random access memory (1T-DRAM). The asymmetric S/D is produced by the different energies of ion implantation at different depths of the pillar. The window of latch voltage ($\Delta {V}_{L}$), which is the difference between the latch-up voltage (${V}_{\textit {LU}}$) and latch-down voltage (${V}_{\textit {LD}}$), was dominantly governed by ${V}_{\textit {LD}}$. Fluctuation in the $\Delta {V}_{L}{(}{=}{V}_{\textit {LU}} - {V}_{\textit {LD}}$) is mainly induced by different series resistances (${R}_{\textit {SD}}$). The variation in ${R}_{\textit {SD}}$ becomes increasingly fatal to the stable operation of a 1T-DRAM with a smaller diameter; therefore, uniform control of ${R}_{\textit {SD}}$ is very important for the read operation in 1T-DRAM. In addition, the doping concentration of the source should be high for wide $\Delta {V}_{L}$. [ABSTRACT FROM AUTHOR]

This paper proposes the multi-material topology optimization for the simultaneous design of segmented permanent magnet (PM) arrays, coil, and iron materials in magnetic actuators. Specifically, the proposed approach can find the optimal layout and shape of PM, coil, and iron materials, as well as the optimal border and magnetization direction of segmented PM arrays. For designing the layout and shape of actuator components, the discrete material optimization-type material interpolation scheme is employed in this paper. To attain the design of segmented PM arrays, an orientation design variable in Cartesian coordinate is utilized with the penalization scheme for the discrete PM magnetization directions. To validate the effectiveness of the proposed actuator design approach, two numerical examples are presented. In the examples, the actuator components (i.e., segmented PM arrays, coil winding, and back iron) are designed aiming for maximizing the magnetic force magnitude acting on the actuator plunger. [ABSTRACT FROM AUTHOR]

The hot-carrier degradation of the junctionless mode (JM) and the inversion mode (IM) of five-story vertically integrated gate-all-around (GAA) MOSFETs is investigated for the first time. It is found that the degradation of drain current induced by the hot-carrier injection (HCI) in the JM-FET is less than that in the IM-FET for the same dimensions and bias conditions, because of the bulk conduction mechanism of the JM-FET, which is in contrast to surface conduction of the IM-FET. The results are obtained using electrical measurements and numerical simulations. The analysis of how HCI affects the lifetime reliability of vertically integrated GAA MOSFETs is of great importance for ultimate scaling of the silicon transistor. [ABSTRACT FROM PUBLISHER]

The low-frequency noise (LFN) characteristics of a vertical pillar-type FET were investigated in order to observe the different influences of the source resistance ( RS) and the drain resistance ( RD) . Because of its inherent vertical channel structure, the RS and RD are inevitably different. To observe the effects of the asymmetric RS and RD on LFN, a forward mode (FM) and reverse mode (RM) of voltage sweep were used. In the RM, the correlated mobility fluctuation effect was higher and the power spectral density of resistance fluctuation ( S\mathrm{ RSD}) was lower than those in the FM. In addition, S\mathrm{ RSD} was correlated with the RS , but little with the RD . To suppress S\mathrm{ RSD} , it is important to minimize the RS . [ABSTRACT FROM AUTHOR]

We present an isogeometric shape optimization method for the design of magnetic actuators. The objective is to maximize the magnetic force of actuators, which tends to be highly dependent on the geometry around air gap. The isogeometric shape optimization is known to be robust for the actuator design, since it can preserve the exact geometry during the design optimization. Using the Maxwell stress tensor method, the magnetic force is calculated through the isogeometric analysis. The analytical design sensitivity provides geometric exactness due to the use of non-uniform rational B-splines basis functions. The optimization problem is solved using a gradient-based algorithm of modified method of feasible directions. To demonstrate the robustness of the isogeometric method, the geometric dependence of magnetic forces is investigated. In addition, the isogeometric optimization method is applied to the design problems of linear and rotating actuators, which yields the optimal shape of the ferromagnetic materials around the air gap. [ABSTRACT FROM AUTHOR]