Nonvolatile charge storage memory based on $MoS_2$ and iCVD polymer dielectric

Abstract

Recently, one of transition metal dichalcogenides (TMDCs), molybdenum disulfide ($MoS_2$) has been regarded as a rising semiconductor materials in electronics, optoelectronics, and flexible or transparent device applications because of their special natural peculiarities due to thin atomically thin thickness and layered structure with band gap properties. Among the many applications of $MoS_2$, the development of flexible nonvolatile memory is promising for its important position in electronic systems to store the data flood related with wearable devices in internet of things (IoT) era. However, the effective charge storage and memory performance, such as endurance cycling and retention characteristics, remain to be solved. To enhance a reliable characteristics of nonvolatile memory, we investigated the $MoS_2$ based charge storage memory with a gate stack of metal nanoparticles and poly(1,3,5-trimethyl-1,3,5-trivin yl cyclotrisiloxane) (pV3D3) dielectric materials which were utilized as a charge storage, tunneling oxide respectively. A highly uniform, flexible and pure polymer layer via initiated chemical vapor deposition (iCVD) process was deposited to overcome the limitation of atomic layer deposition (ALD) process on zero dangling bond surface of the $MoS_2$. The gold nanoparticles was used for the charge storage layer via thermal evaporation method to maximize the memory characteristics. The high-k $Al_2O_3$ by ALD process worked as the blocking dielectric with particular purpose to increase the gate coupling ratio with low-k pV3D3 layer. The fabricated memory device exhibits a tunable memory window with a high on/off $(~10^5)$ ratio, a high endurance of a thousand cycling, and a long retention characteristics $(~10^5 s)$. This research provides a future approach to the development of a flexible and wearable nonvolatile memory application based on two dimensional materials with iCVD polymer dielectric layers.