Resistive Switching in a MoSe₂-Based Memory Device Investigated Using Conductance Noise Spectroscopy

Abstract

Resistive random access memory (RRAM) devices are widely considered promising candidates for future memory and logic applications. Though their excellent performances have been reported over the years, resistive switching due to various charge conduction mechanisms is still being debated. Here, we report systematic investigations on resistive switching in a MoSe2-based nonvolatile bipolar memory device by measuring current–voltage characteristics and using low-frequency conductance noise spectroscopy in both low and high resistive states. The memory device was fabricated in a metal–insulator–metal configuration by mixing MoSe2 nanoflakes in a poly­(methyl methacrylate) (PMMA) matrix sandwiched between the top and bottom electrodes. The device shows an appreciable retention capacity and long cycle endurances in the low resistive state (LRS)/high resistive state (HRS) in repeated measurement cycles. The low-frequency conductance fluctuation power spectra show 1/f noise characteristics in the low resistive state and 1/f 2 behavior in the high resistive state. The 1/f 2 characteristics of the noise power spectra indicate the presence of random telegraphic noise. The stochastic analysis of the current fluctuation in the high resistive state further confirms that the enhanced random telegraphic noise originates from the transport of charge carriers by trap-assisted tunneling in the MoSe2@PMMA matrix.

Nonlinear Coherent Light–Matter Interaction in 2D MoSe2 Nanoflakes for All‐Optical Switching and Logic Applications

“…The detailed preparation method of MoSe 2 NFs has been discussed in our earlier works. [28,57] In brief, a suitable amount of sodium molybdate (Na 2 MoO 4 • 2H 2 O) was added in 22.5 mL dimethylformamide (DMF) solution with 30 min sonication for proper dispersion at room temperature. Next, 15 mg of selenium powder was dispersed in 7.5 mL hydrazine hydrate by constant stirring in an oil bath at 80 °C for 1 h. Then, this solution was mixed with the previously prepared DMF solution to maintain the atomic ratio of Mo:Se as 1:2.…”

Optoelectronic Memristive Synapse Behavior for the Architecture of Cu2ZnSnS4@BiOBr Embedded in Poly(methyl methacrylate)

“…In the low-bias condition (0 to −0.53 V), the electric field-injected charges in the CZTS@BOB-PMMA memristive layer are much lower than that of hot carriers; thus, the dominant conduction is mainly the hot-excited carriers, leading to linear Ohmic conduction ( I ∝ V ). While with high applied voltage (−0.53 to 0.64 V), according to Child’s law ( J , current density; ε, dielectric constant; μ, electron mobility; d , thickness of the memristive layer) the fitting result ( I ∝ V 2 ) indicates the charge transport behavior is in good agreement with the trap-assistant SCLC mode, as illustrated in Figure d . After the injected charges fill the traps and could move freely to form conductive channels in the CZTS@BOB-PMMA layer, the device would be set into the LRS state.…”

“…31 In the low-bias condition (0 to −0.53 V), the electric field-injected charges in the CZTS@BOB-PMMA memristive layer are much lower than that of hot carriers; thus, the dominant conduction is mainly the hot-excited carriers, leading to linear Ohmic conduction (I ∝ V). While with high applied voltage (−0.53 to 0.64 V), according to Child's law (J, current density; ε, dielectric constant; μ, electron mobility; d, thickness of the memristive layer) 21 = J V d…”

“…20 On this basis, as electron trapping/detrapping centers, inorganic materials, such as MoSe 2 and Fe 3 O 4 , can be inserted into PMMA to obtain resistive switching behaviors. 21,22 From another perspective, two-dimensional (2D) materials (e.g., MoS 2 , WS 2 , BN, BiOI) can also be coated on substrates to be applied in memristors using their advantages of charge separation and transfer. 23−26 In view of the easily regulated microstructures, especially the intrinsic interlaminar electrostatic fields between layers of positive [Bi 2 O 2 ] 2+ and negative bromide ions for efficient charge separation and transfer, ternary bismuth oxybromide (BiOBr, BOB, bandgap ∼2.5−2.9) was widely studied in photocatalysis.…”

“…Organic insulating poly­(methyl methacrylate) (PMMA) has been introduced in the medium layer to improve the performance reliability and long-term stability due to its small Young’s modulus, low processing temperature, and easy packaging . On this basis, as electron trapping/detrapping centers, inorganic materials, such as MoSe 2 and Fe 3 O 4 , can be inserted into PMMA to obtain resistive switching behaviors. , From another perspective, two-dimensional (2D) materials (e.g., MoS 2 , WS 2 , BN, BiOI) can also be coated on substrates to be applied in memristors using their advantages of charge separation and transfer. − In view of the easily regulated microstructures, especially the intrinsic interlaminar electrostatic fields between layers of positive [Bi 2 O 2 ] 2+ and negative bromide ions for efficient charge separation and transfer, ternary bismuth oxybromide (BiOBr, BOB, bandgap ∼2.5–2.9) was widely studied in photocatalysis. − As such, BOB should have extensive research attention as the resistive layer in memristors, but so far, there are few reports on it. In this work, for 2D sheet-like BOB, by coupling p-type narrow-band photosensitive Cu 2 ZnSnS 4 (CZTS, ∼1.5 eV) to compensate for its low excitation of O 2p orbital which inhibits extending the spectral response, the CZTS@BOB is embedded in PMMA film acting as switching layers.…”