Seongjae Cho

Scaling Effect on Silicon Nitride Memristor with Highly Doped Si Substrate

A feasible approach is reported to reduce the switching current and increase the nonlinearity in a complementary metal-oxide-semiconductor (CMOS)-compatible Ti/SiNx /p+ -Si memristor by simply reducing the cell size down to sub-100 nm. Even though the switching voltages gradually increase with decreasing device size, the reset current is reduced because of the reduced current overshoot effect. The scaled devices (sub-100 nm) exhibit gradual reset switching driven by the electric field, whereas that of the large devices (≥1 µm) is driven by Joule heating. For the scaled cell (60 nm), the current levels are tunable by adjusting the reset stop voltage for multilevel cells. It is revealed that the nonlinearity in the low-resistance state is attributed to Fowler-Nordheim tunneling dominating in the high-voltage regime (≥1 V) for the scaled cells. The experimental findings demonstrate that the scaled metal-nitride-silicon memristor device paves the way to realize CMOS-compatible high-density crosspoint array applications.

Simulation of One-Transistor Dynamic Random-Access Memory Based on Symmetric Double-Gate Si Junctionless Transistor

In this study, one-transistor dynamic random-access memory (1T-DRAM) based on a symmetric double-gate Si junctionless transistor is proposed using technology computer-aided design simulation. The proposed device uses double gates that play different roles in realizing 1T-DRAM operation. Gate 1 is used as a switching node, and Gate 2 is used as a storage node. By controlling the different two gate workfunctions, a potential barrier is adjusted to store hole effectively. The operation characteristics were investigated regarding four different memory operation states to write 1, write 0, read, and hold. Also, the effects of two different gate workfunctions on sensing margin and retention characteristics are closely investigated. Through a set of optimally set gate workfunctions, 33 μA/μm of sensing margin and 38 ms of retention time have been obtained.