Controlled charge trapping by molybdenum disulphide and graphene in ultrathin heterostructured memory devices

Abstract

Atomically thin two-dimensional materials have emerged as promising candidates for flexible and transparent electronic applications. Here we show non-volatile memory devices, based on field-effect transistors with large hysteresis, consisting entirely of stacked two-dimensional materials. Graphene and molybdenum disulphide were employed as both channel and charge-trapping layers, whereas hexagonal boron nitride was used as a tunnel barrier. In these ultrathin heterostructured memory devices, the atomically thin molybdenum disulphide or graphene-trapping layer stores charge tunnelled through hexagonal boron nitride, serving as a floating gate to control the charge transport in the graphene or molybdenum disulphide channel. By varying the thicknesses of two-dimensional materials and modifying the stacking order, the hysteresis and conductance polarity of the field-effect transistor can be controlled. These devices show high mobility, high on/off current ratio, large memory window and stable retention, providing a promising route towards flexible and transparent memory devices utilizing atomically thin two-dimensional materials.

Recent Advances in Electronic and Optoelectronic Devices Based on Two-Dimensional Transition Metal Dichalcogenides

“…In addition, a new type of the memory device was fabricated with graphene (G) as the FET channel, hBN (B) as the tunnel barrier, and MoS 2 (M) as the charge trapping layer (denoted as GBM) [253,254]. This result confirmed that the MoS 2 layer could act as an effective charge-trapping layer.…”

“…When a thicker MoS 2 layer and thinner hBN were employed, unipolar conductance and greater hysteresis were observed due to effective electron tunneling and electric-field screening. In addition, the reversed stacking structure (MBG) was also investigated, with a high on/off current ratio and a large memory window [253]. Due to the time-dependent PL, the MoS 2 -graphene heterostructure can also function as a rewritable optoelectronic switch or memory, where the persistent state shows almost no relaxation or decay within experimental timescales, indicating near-perfect charge retention [255].…”

Production Methods of Van der Waals Heterostructures Based on Transition Metal Dichalcogenides

“…As the family of 2D materials is increasing gradually in recent years, this kind of heterostructures allows a greater freedom and a far greater number of combinations than any traditional growth method. Furthermore, van der Waals heterostructures have already led to the observation of numerous exciting physical phenomena and novel applications such as correlated light emitters [28][29][30][31], ultra-high speed photodetectors [32,33], new generation field effect transistors [34][35][36][37], and memory devices [38][39][40][41] compared to their individuals. Therefore, the investigation of van der Waals heterostructures shows great importance.…”

Selective and efficient electrochemical biosensing of ultrathin molybdenum disulfide sheets

“…Molybdenum disulfide (MoS 2 ) has been one such extensively studied and revisited material since its first report by Joesen et al in 1986 [5][6][7][8]. After the successful demonstration of MoS 2 -based field-effect transistors, and following many other interesting electronic and optoelectronic applications [9][10][11], various methods have evolved for the synthesis of good-quality MoS 2 atomic layers. Liquid exfoliation of bulk crystals for getting atomic thin layers can be successfully optimized to produce large amounts of layered materials [12,13].…”