Preparation and characterisation of amorphous Cu:7,7,8,8-Tetracyanoquinodimethane thin films with low surface roughness via thermal co-deposition

We demonstrate a physical vapor deposition process for preparing amorphous Cu:Tetracyanoquinodimethane (Cu:TCNQ) thin films. Samples made by this co-evaporation process exhibit a smooth surface in the scanning electron microscope. Spectroscopic studies confirmed the formation of a charge transfer (CT) complex with a degree of CT of 0.68. Reproducible resistive switching is observed in a glass/NiCr/Al/Cu:TCNQ/Al sandwich structure. OFF/ON ratios of 10 to 10(2) and impedance values between 100 k Omega and 10 M Omega have been measured. Switching voltages for the prepared samples with a film thickness of around 100 run are in the range of 4 +/- 2 V and are fairly symmetrical. The devices have a life time of more than 10(4) switching cycles. (c) 2006 Elsevier B.V. All rights reserved.