Controlling the Carrier Injection Efficiency in 3D Nanocrystalline Silicon Floating Gate Memory by Novel Design of Control Layer

Abstract

Three-dimensional NAND flash memory with high carrier injection efficiency has been of great interest to computing in memory for its stronger capability to deal with big data than that of conventional von Neumann architecture. Here, we first report the carrier injection efficiency of 3D NAND flash memory based on a nanocrystalline silicon floating gate, which can be controlled by a novel design of the control layer. The carrier injection efficiency in nanocrystalline Si can be monitored by the capacitance–voltage (C–V) hysteresis direction of an nc-Si floating-gate MOS structure. When the control layer thickness of the nanocrystalline silicon floating gate is 25 nm, the C–V hysteresis always maintains the counterclockwise direction under different step sizes of scanning bias. In contrast, the direction of the C–V hysteresis can be changed from counterclockwise to clockwise when the thickness of the control barrier is reduced to 22 nm. The clockwise direction of the C–V curve is due to the carrier injection from the top electrode into the defect state of the SiNx control layer. Our discovery illustrates that the thicker SiNx control layer can block the transfer of carriers from the top electrode to the SiNx, thereby improving the carrier injection efficiency from the Si substrate to the nc-Si layer. The relationship between the carrier injection and the C–V hysteresis direction is further revealed by using the energy band model, thus explaining the transition mechanism of the C–V hysteresis direction. Our report is conducive to optimizing the performance of 3D NAND flash memory based on an nc-Si floating gate, which will be better used in the field of in-memory computing.

Editorial for the Special Issue “Amorphous and Nanocrystalline Semiconductors: Selected Papers from ICANS 29”

“…This includes topics such as Si-based, oxide, perovskite, 2D thin films and nanostructures, device applications for TFTs, solar cells, and LEDs, as well as memory devices and emerging flexible electronics and neuromorphic applications. For example, new fabrication technologies of amorphous and nanocrystalline thin films, electronic and optical characteristics, and device applications are presented and discussed in [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ], including theoretical work in an ab initio study [ 9 ], controllable growth and formation of Si nanowires [ 1 ], nanocrystals [ 2 ], and quantum dots [ 3 , 4 ]. There are also several papers that cover emerging memory devices.…”

“…There are also several papers that cover emerging memory devices. These include phase change memory [ 5 , 6 , 7 , 8 , 9 ] based on amorphous chalcogenide thin films and memristors based on transition metal oxides acting as an artificial synapse [ 10 , 11 , 12 ]; the improvement of electro-luminescence (EL) efficiency Er-doped oxide thin films [ 13 , 14 , 15 ]; 2D semiconductor thin films and perovskite for solar cells and aqueous Zn-air battery [ 16 , 17 , 18 , 19 ]; and flexible electronic materials for integrated strain sensors [ 20 , 21 ]. We anticipate that this Special Issue should interest a broad audience in these related fields.…”

“…In addition, they [ 11 ] described the a-SiNx:H-film-based resistive switching memory and used the transient current measurements to discover the Si dangling bonds nanopathway in a-SiNx:H resistive switching memory. Moreover, they [ 12 ] also employed the capacitance–voltage (C-V) measurements to investigate how to control the carrier injection efficiency in 3D nanocrystalline Si floating gate memory.…”