Systematic Design and Demonstration of Multi‐Bit Generation in Layered Materials Heterostructures Floating‐Gate Memory

Abstract

Van der Waals (vdW) heterostructures with 2D materials have shown that atomically thin non‐volatile memories are advantageous in terms of integration, while offering high performance and excellent stability. The non‐volatile memory behavior of 2D materials has mainly been studied for single‐bit operation, and there is growing interest in expanding to multi‐bit operation to enhance the storage capacities of memory devices. However, the conditions or rules for generating the desired number of bits in 2D‐based multi‐bit memory remain to be identified. In this study, multiple bits are successfully created on non‐volatile memory based on vdW heterostructure floating‐gate memory (FGM) by systematically tuning the dimensions of the 2D materials. In particular, a fingerprint mechanism is established that links the bit number and dimensions of 2D crystals on vdW heterostructures. This approach could enable the precise generation of the desired number of bits in layered‐material‐based vdW FGMs.

Electron Tunneling Enhancement in MoS2/Hexagonal Boron Nitride/Multilayer Graphene Heterostructures by Bubble Formation

“…This △𝑉 CPD value can be attributed to molecules trapped in bubbles at the hBN/MLG interface. The tunneled carrier density has shown enhancement through hBN from MLG to MoS 2 layers in MoS 2 /hBN/MLG heterostructures by residues such as water or hydrocarbon (i.e., bubbles) [9].…”

“…The resulting MoS 2 /hBN/MLG heterostructure was employed as a memory device with electron transfer between the MLG and MoS 2 layers, leading to hysteresis in the transport curves for the MoS 2 channel according to the forward (+) and backward (-) sweeps of 𝑉 BG . We considered the hysteresis as the MW [9,29].…”

“…Such residues are commonly referred to as bubbles. Previous studies on bubbles have considered their influence on tunneling [17][18][19][20][21][22][23][24], and we have previously reported the charge trap by bubble formation in a TMDC/hBN/ MLG heterointerface [9]. We observed the tunneling carrier density through the hBN area that includes bubble formation and analyzed an additional charge trapping layer for electron transfer between TMDC and MLG layers in TMDC/hBN/MLG heterostructures.…”

“…Floating gate memory (FGM)-based two-dimensional (2D) material heterostructures can achieve high performance and stability [1][2][3][4][5][6][7][8][9]. For instance, the transition-metal dichalcogenide (TMDC) semiconductor channel, hexagonal boron nitride (hBN) dielectric layer, and multilayer graphene (MLG) semimetal layer heterostructure have been demonstrated and widely used in FGM devices [1][2][3][4][5][6][7][8][9]. The program and erase steps in memory can be achieved by electron tunneling between the TMDC channel and MLG heterostructure through the hBN barrier.…”

“…The program and erase steps in memory can be achieved by electron tunneling between the TMDC channel and MLG heterostructure through the hBN barrier. Hence, the tunneling condition of hBN in a TMDC/hBN/ MLG heterostructure is important in FGM applications [1][2][3][4][5][6][7][8][9].…”