Morphology and Electronic Properties of Hybrid Organic-Inorganic System: Ag Nanoparticles Embedded into CuPc Matrix

I.M. Aristova, O.Yu. Vilkov, A. Pietzsch, M. Tchaplyguine, O.V. Molodtsova, V.Yu. Aristov

European XFEL GmbH Hamburg, Germany & Institute of Solid State Physics Russian Academy of Sciences Chernogolovka, Russia.
HASYLAB DESY Hamburg, German.
Helmholtz Zentrum Berlin Mat&Energy Berlin, Germany.
Institute of Solid State Physics Russian Academy of Sciences Chernogolovka, Russia.
Lund University MAX-lab Lund, Sweden.

DOI: 10.4236/ampc.2012.24B017                

Abstract

Materials with a high on-off resistance ratio could become the basis for resistive random-access memory (RRAM). It is assumed that one of RRAM types can be based on hybrid organic-inorganic systems, while particular attention is focused on hybrid systems consisting of metal nanoparticles (NP) embedded in organic matrix (OM). In this investigation we created and studied the hybrid organic-inorganic systems made of metal (Ag) nanoparticles embedded in organic semiconductor material CuPc. The LEED patterns and NEXAFS data demonstrate that the CuPc films deposited on Au(001) substrate are highly ordered and molecular planes lie parallel to the gold surface. The metal atoms were deposited on the outer surface of the organic molecular film and self-assembled into nanoparticles due to surface and bulk diffusion. The properties of nano-composite materials seem to be significantly dependent on the microstructure, i.e. the size, concentration, bulk- and size-distribution of nanoparticles; therefore we have studied by high resolution transmission electron microscopy the evolution of morphology of nano-composite films as a function of nominal metal deposition. The filled and empty electronic states of the hybrid organic-inorganic systems, energy level alignment at interfaces formed between metal nanoparticles and the organic semiconductor CuPc as well as the chemical interaction at the NP/OM interface were studied by UPS, XPS and NEXAFS methods.

 

Keywords

Hybrid Materials; Nanoparticles; Organic Matrix; Morphology; Electronic Properties; Nonvolatile Memory

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Z. Liu, A.A. Yasseri, J.S. Lindsey, D.F. Bocian, Molecular Memories That Survive Silicon Device Processing and Real-World Operation, Science, vol. 302, 2003, pp. 1543-1545.
[2]	J.C. Scott, Is There an Immortal Memory?, Science, vol. 304, 2004, pp. 62-63; J.C. Scott and L.D. Bozano, Nonvolatile Memory Elements Based on Organic Materials, Adv. Mater., vol. 19, 2007, pp. 1452-1463.
[3]	L.D. Bozano, B.W. Kenan, M. Beinhoff, K.R. Carter, P.M. Rice, J.C. Scott, Organic materials and thin-film structures for cross-point memory cells based on trapping in metallic nanoparticles, Adv. Funct. Mater., vol. 15, 2005, pp. 1933-1939.
[4]	Y.Yang, J.Ouyang, L. Ma, R.J.-H. Tseng, C.-W. Chu, Electrical Switching and Bistability in Organic/Polymeric Thin Films and Memory Devices Adv. Funct. Mater., vol. 16, 2006, pp. 1001-1014.
[5]	D. Prime, S. Paul, and P.W. Josephs-Franks, Gold nanoparticle charge trapping and relation to organic polymer memory devices, Phil. Trans. R. Soc., vol. A367, 2009, pp. 4215-4225.
[6]	J.Y. Ouyang, C.W. Chu, C.R. Szmanda, L. Ma and Y. Yang, Programmable polymer thin film and non-volatile memory device, Nat. Mater., vol. 3, 2004, pp. 918-922.
[7]	D. Tondelier, K. Lmimoumi, C. Fery, and G. Haas, Metal/organic/metal bistable memory devices, Appl. Phys. Lett., vol. 85, 2004, pp. 5763-5765.
[8]	L. D. Bozano, B. W. Kenan, V. R. Deline, J. R. Salem, and J. C. Scott, Mechanism for bistability in organic memory elements, Appl. Phys. Lett., vol. 84, 2004, pp. 607-609.
[9]	H. Peisert, T. Schwieger, J. M. Auerhammer, M. Knupfer, M. S. Golden, J. Fink, P. R. Bressler, and M. Mastet al., Order on disorder: Copper phthalocyanine thin films on technical substrates, J. Appl. Phys., vol. 90, 2001, pp. 466-469.
[10]	G. Cabailh, J. W. Wells, I. T. McGovern, A. R. Vearey-Roberts, A. Bushell, and D. A. Evans Synchrotron radiation studies of the growth and beam damage of tin-phthalocyanine on GaAs(001)-1x6 substrates, Appl. Surf. Sci., vol. 234, 2004, pp. 144-148.