Conductance quantization in a Ag filament-based polymer resistive memory

Abstract

Resistive switching and conductance quantization are systematically studied in a Ag/poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester/indium-tin oxide sandwich structure. The observed bipolar switching behavior can be attributed to the formation and dissolution of Ag filaments during positive and negative voltage sweeps, respectively. More importantly, conductance quantization with both integer and half integer multiples of single atomic point contact can be realized by slowing down the voltage sweep speed as well as by pulse measurement. The former may reflect the formed Ag filaments with different atomic point contacts, while the latter probably originates from the interaction between the Ag filaments and the elemental hydrogen provided by the organic storage medium. With appropriate current compliances, low resistance states with desired quantized conductance values are successfully achieved, thus showing the potential for ultrahigh density memory applications. Besides, 100 successive switching cycles with densely distributed resistance values of each resistance state and extrapolated retention properties over ten years are also demonstrated.

Conductive-bridge memory (CBRAM) with excellent high-temperature retention

“…This picture [7] is based on the observation [12] that, for a sufficiently high write current, the ON-state conductance of Ag/GeS 2 cells tends to be an integer multiple of G 0 =2e 2 /h (Fig. 3), as observed earlier in gap-type "atomic switches" [14] and recently in many other types of gapless cells [15][16][17][18][19][20][21][22]. Quantization of the conductance implies Fig.…”

Appearance of quantum point contact in Pt/NiO/Pt resistive switching cells

“…In recent years, observation of quantized conductance discrete steps characterized by integer or half integer multiples of G 0 5 2e 2 /h has been reported in ECMs 8,[12][13][14][15][16][17][18] and VCMs. [19][20][21][22][23] While there is a few studies on the conductance quantization effect in TCMs, 14,24 we have reported that a conductive filament including a quantum point contact (QPC) can be formed in Pt/NiO/Pt RS cells.…”

Resistive switching and conductance quantization in Ag/SiO2/indium tin oxide resistive memories

“…[9][10][11][12] Essentially, conductance quantization is seen during ballistic electron wave transmission through a constriction with a lateral dimension that is comparable to the Fermi wavelength of the electrons. 1 In the research field of RRAMs, conductance quantization means that the conductance (G) of a RRAM cell in the LRS can be expressed as G ¼ nG 0 (n ¼ 1, 2, 3, …), where G 0 ¼ 2e 2 /h % 77.5 lS (e is the electron charge and h is Planck's constant) refers to a single atomic point contact.…”

“…Due to the absorption of impurities on or in the conducting filaments, half-integer quantized conductance values, i.e., G ¼ (n À 1/2)G 0 , are also frequently observed. 10,12 It is apparent that multilevel storage will be easily realized if these quantized conductance values can be well controlled. Up to now, conductance quantization has been reported only in several RRAM systems, which can be classified into two categories based on the switching mechanisms.…”