Jiang Nan

Low on/off ratio gravely hinders the application of magnetoresistance (MR) devices for the accurate and reliable data fetch. In this paper, a rectified tunnel MR (R-TMR) device is fabricated by integrating perpendicular-magnetic-anisotropy magnetic tunnel junction (PMA MTJ) and Schottky diode. High on/off ratio, intrinsic non-volatility and multi-dimensional regulation capabilities can be obtained, which makes this emerging spintronic device suitable for in-memory computing (IMC). By reversing the rectifying direction of the diode and tuning the proportions of alternating current (AC) and direct current (DC), reconfigurable logic operations have been achieved. Two proofs of concept, i.e. “NOR” and “NAND”, are experimentally performed.

Information storage and transfer via current-induced domain wall (DW) motions exhibit significant density-speed-energy advantages, which inspires numerous emerging devices and circuits, such as racetrack memory (RM). However, the bi-directional propagation of DWs in the conventional tape-shaped nanowire will lead to data overflow issue, implicitly deteriorating storage density and operational performances. In this paper, we propose a non-volatile cache design based on spin-orbit torque-driven ring-shaped RM. The systematical investigations, covering from device modeling, to circuits design, to bit-cell layout design, and to system evaluation have been carried out. Thanks to the cells-overlapping design, the proposed RM L2 cache can achieve 48×, 16×, and 8× improvements in term of capacity, compared with iso-area caches based on static random access memory (SRAM), spin transfer torque magnetic RAM (STT-MRAM), and tape-shaped RM, respectively. As proved by 4-core system experiment results, the proposed RM cache can improve 30.7% instructions per cycle (IPC) and save 58.2% energy compared with SRAM cache.

In this work, the performance of single layer MoS2 double gate transistors with metallic contacts is evaluated with quantum ballistic calculation. The image force which is crucial for accurate simulation of Schottky barrier is taken into account. The simulation results reveal that increasing doping concentration is the most effective way to adjust transistor performance, and device performance of transistors with metallic contacts can be comparable and even outperforms that with ohmic contacts.