A novel approach towards molecular memory device in gate tunable structure of MoS 2 -graphene
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BSTRACT Molecular interaction in two-dimensional (2D) van der Waals (vdW) interfaces has drawn tremendous attention for extraordinary materials characteristics. So far sensing characteristics of molecular interaction has been exploited extensively to reach the detection limit to a few parts-per-billion (ppb) of molecules and far less attention is given to the evolution of persistent current state due to the molecular exposure. Our study focuses on molecular memory operation of MoS2-graphene heterostructure based field effect transistor. Metastable resistance state of the device due to the external perturbation of molecules is tuned to get a nearly relaxation free current state at much lower molecular concentration of 10 ppb to facilitate non-volatile memory features for molecular memory operation. An ultrafast switching operation in milli-second order is achieved at room temperature for the fastest recovery obtained so far in any molecular sensor. The process is co-controlled both by molecular as well as external charge density.
KEYWORDS MoS2, graphene, field effect transistor, molecular memory, trap charges
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Introduction
The past few decades have seen a tremendous growth in memory devices which constitutes the basis of modern electronic information. However, both the magnetic and electrically controlled programable charge storage device operations are not popular due to the physical and technical limitations [1–4]. Several reports have shown gate charge trap memorybased operation for multibit charge storage [5, 6]. Recently optoelectronic storage devices have grown a significant interest not only due to their non-volatile charge storage capacity but also allow the manipulation of light activated logic gates by light-matter interaction [7–10]. These achievements greatly promote the development of low-dimensional hybrid systems in the field of molecular memory device. Other than uses of light in optoelectronic based memory systems, the molecular stimulus represents another powerful input for molecular activated logic gates, recording, computing, programmable logic circuits at room temperature [11−13]. Alternatively, molecular memory has the potential to work in molecular scale and therefore promises for low power memory devices which can be tailored by the molecular interaction. So far molecular interactions are limited predominantly on emphasizing sensor response, sensitivity and the detection limit of molecular sensors [14–21] However, far less attention is given to the fact that most of the sensors lack fast recovery due to a permanent shift in base resistance of the material upon molecular exposure leading to a persistent current state [22–24]. This slowly relaxing state is observed in case of carbon-based materials, semiconductors and heterojunctions which are the materials to be potentially utilized as a programable charge storage Address correspondence to [email protected]
devices [25–27]. Gas-phase detection involving atomically thin transitionmetal dichalcogenides channels, especially molybdenum dis
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