On the origin of bistable resistive switching in metal organic charge transfer complex memory cells

Abstract

Electrical characteristics of Cu:tetracyanoquinodimethane (TCNQ) devices with different electrodes were studied. The comparison of impedance spectroscopic measurements on devices with Al and Pt top electrodes proved the existence of a high resistive interface layer between Cu:TCNQ and Al. An equivalent circuit was modeled and the resulting values suggest that the interface layer is composed of naturally formed aluminum oxide. Devices with deliberately formed aluminum oxide and without Cu:TCNQ were fabricated and revealed a similar behavior. The authors propose that the switching effect in Cu:TCNQ thin film devices is a Cu ion based electrochemical effect occurring in a thin aluminum oxide layer.

Universality of non-Ohmic shunt leakage in thin-film solar cells

“…55͒ or Cu:TCNQ. 56 Interestingly, in their OFF state, these memories exhibit a symmetric non-Ohmic current similar to the shunt in OPV cells. Note that PEDOT-:PSS is commonly used as an interfacial layer in organic BHJ solar cells, 26 and we suspect it, as well as substrate defects, may be involved in the formation of shunt paths.…”

Mechanism for resistive switching in chalcogenide-based electrochemical metallization memory cells

“…1,2 The ECM cell consists of an insulator layer sandwiched between two electrodes, in which one is made from an electrochemically active electrode (AE) metal, such as Ag or Cu, and the other is a counter electrode (CE), such as Pt, Ir, W, or Ag. 3,4 Till now, a large number of ECM cells have been reported, employing various insulating materials such as chalcogenides, [5][6][7][8][9][10][11][12][13] oxides, [14][15][16][17][18][19][20][21][22][23][24] amorphous Si (Refs. 25 and 26) and C, [27][28][29][30] and organic materials.…”

Solution growth of metal-organic complex CuTCNQ in small dimension interconnect structures

“…For these reasons the chemical reaction of TCNQ with a (patterned) Cu substrate seemed for us to be the best suited method, since the material is only formed at the interface of the (patterned) metal. To complement previous works on CuTCNQ nanowires [7,13,22] and dense films [10,23], we report in this paper two different routes to grow CuTCNQ complex in liquid phase within small via holes opened in SiO 2 /SiC stack. The basic common idea relies on the formation of CuTCNQ material from the partial and controlled corrosion of a Cu bottom electrode by a TCNQ-based solution.…”

“…The best experimental conditions -corresponding to a low solubility of the formed Cu + TCNQ -charge transfer complex and sufficient high solubility of TCNQ (1 mg/ml) -were obtained with acetonitrile/2-butanone mixture in 5:95 volume ratio. Several reaction times (10,20,30 or 40 s) were tested to optimize conditions for the CuTCNQ growth process and to apprehend via hole filling. Once again, the formation of CuTCNQ complex was checked by Raman spectroscopy: the measured spectrum was very similar to the one obtained on CuTCNQ nanocrystals [27] crystallizing in phase I [28].…”

“…Recently, the switching was attributed to the formation and dissolution of Cu filaments through a native oxide layer formed at the interface between CuTCNQ complex and an oxidizable metal (e.g. aluminum) used as top electrode [8][9][10][11].…”