Search

High-density integration of ferroelectric field-effect transistors (FeFETs) is hindered by factors such as interfacial states, short-channel effects, and ferroelectricity degradation in ultrathin films. Accordingly, the introduction of two-dimensional (2D) materials could effectively solve these problems. However, most current studies focus on the replacement of Si-based channels with 2D channels. Little progress has been made in addressing issues caused by bulk-phase ferroelectric gate layers, such as the unavoidable rough interfaces and the fading of ferroelectricity in ultrathin films. Herein, the 2D ferroelectric material In2Se3 is introduced as the gate dielectric. Combined with 2D insulating h-BN and 2D channel MoS2, an all-van der Waals (vdW) stacking FeFET is fabricated to provide a straight solution for the abovementioned issues. First, the robust ferroelectric phase of In2 Se3 is verified in an ultrathin film case and a high-temperature case, which is outstanding among recently reported 2D ferroelectrics. Second, device-level out-of-plane ferroelectric polarization switching is achieved in the cross-structure device. Based on these results, In2 Se3 is adopted as the ferroelectric gate dielectric to fabricate all-vdW stacking FeFETs. The subsequent transistor performance measurement on the fabricated FeFETs indicates that the ferroelectric polarization of the In2 Se3 layer plays a dominating role in forming a counterclockwise hysteresis loop. Further pulse response measurements manifest the feasibility of nonvolatile channel conductance tuning of these devices with a proper pulse design. Our findings suggest that In2Se3 is a suitable 2D ferroelectric gate material and that all-vdW stacking FeFETs based on 2D ferroelectrics are promising in the application of high-density memory. [ABSTRACT FROM AUTHOR]

In this paper, we proposed an oocyte orientation selection method based on the minimum strain position in the penetration process in order to maximize the developmental potential of the operated oocytes. Considering the symmetry of an oocyte during the penetration process, we analyzed only the intracellular strain of the lower half of the oocyte (from 3 o'clock to 9 o'clock). Firstly, the strain distribution in the penetration process was calculated using the finite element analysis method. The influences of penetration force, zona pellucida thickness, oocyte radius, Young's modulus of the cytoplasm, and zona pellucida on the strain distribution were studied. The simulation results showed that the strain values at the 4 o'clock and 9 o'clock areas were significantly smaller than those at the 5 o'clock, 6 o'clock, 7 o'clock, and 8 o'clock areas. Secondly, the experimental strain distribution during penetration was evaluated for the first time using an optical flow method. The experimental strain distribution was strongly positively correlated to the aforementioned simulated results. Finally, the developmental potential of the penetrated porcine oocyte with different orientations was evaluated using the cleavage rate (48 h after penetration and parthenogenetic activation). The cleavage rate was strongly negatively correlated to the intracellular strain. We inferred that a smaller strain on the polar body areas in the penetration process caused less potential damage, which leads to a higher developmental potential of the penetrated oocyte. The optimized oocyte orientations, with the polar body at the 4 o'clock and 9 o'clock areas, are determined based on the minimum strain position in the penetration process. [ABSTRACT FROM AUTHOR]