Nonvolatile memories by using charge traps in silicon-rich oxides

Abstract

The nonvolatile memory characteristics of silicon-rich oxide (SRO, SiOx) grown at room temperature for charge-trapping layer are first reported and shown to exhibit a strong dependence on oxygen content (x). The memory window that is estimated by capacitance-voltage curves monotonically decreases with increasing x from 1.0 to 1.8, possibly resulting from the x-dependent variation in the Si suboxide states responsible for the charge traps, as evidenced by x-ray photoelectron spectroscopy. The density of the charge traps is estimated to be (3.9–8.8)×1012 cm−2 for x=1.0–1.4. The charge-loss rate sharply decreases at x=1.2, but by further increase in x above 1.2, it gradually increases, which can be explained by the lowered SRO/SiO2 barrier due to the increased optical band gap of SRO at larger x

Visible Light-Erasable Oxide FET-Based Nonvolatile Memory Operated with a Deep Trap Interface

“…The earlier NVM devices included a metal floating gate, as shown in Figure a Figure b shows the Si-oxide-nitride-oxide-Si (SONOS)-type NVM device, where a dielectric material such as silicon nitride replaces the metal floating gate. − In addition, various functional layers have been studied as charge trapping layers or blocking layers in the SONOS structure. , In the SONOS-type memory, the program/erase ability is superior to that of the conventional floating-gate memory. However, because of the presence of the tunneling oxide, a concern arises that the device lifetime would be shortened because of the defects created by repetitive tunneling. , Therefore, the degree of memory integration is limited.…”

Multi-valued charge trapping memory based on amorphous-indium-gallium-zinc oxide thin film transistor with designed Ga 2 O 3 /Al 2 O 3 stack insulator

“…However, by far the a-IGZO TFT charge trapping NVM technology still is immature. In order to improve the memory capacity and get large memory window, a-IGZO TFT charge trapping NVM is actively investigated with gate-stack configurations using different charge storage medium, such as metal nanocrystals [7,8], dielectric (SiN x , SiO x , AlO x ) [9][10][11], and semiconductors (GIZO, ZnO) [12,13]. In this paper, we designed simple Ga 2 O 3 /Al 2 O 3 stack insulator as charge trapping structure of a-IGZO TFT NVM.…”