Hybrid films of Co - C60 preparation and changes induced by external stimuli

TL;DR

This work tackles how external energy inputs reshape immiscible $Co$-$C_{60}$ hybrid films by applying identical growth conditions followed by different post-deposition treatments (vacuum annealing, Ar$^+$ ion irradiation, $C^+$ irradiation, and laser irradiation). A co-deposition fabrication method on $Si(110)$ is combined with comprehensive characterization including $RBS$/$ERDA$, SEM/TEM, Raman spectroscopy, and resistivity measurements to map morphology, composition, and electronic changes. The main finding is that each energy-delivery pathway drives distinct nanostructural evolution and conduction behavior: annealing promotes $C_{60}$ self-assembly and percolative $Co$ pathways with reduced resistance, while irradiation and laser exposure tend to increase disorder, oxidation, and resistance. These results provide a systematic framework for tailoring metal–organic hybrids for electronics, spintronics, and energy applications, and offer a model for studying their long-term evolution under harsh environments.

Abstract

In this work, we report on the study on organic-metal hybrid systems, in particular Co-C60 fullerene thin films. This study mainly focused on the investigation of the morphological and structural evolution of the film surface after various external stimuli designed to provide energy to the system. For film growth, we adopted an innovative approach, combining ion-beam sputtering of a pure metal target with thermal evaporation of C60 in a co-deposition setup. The films underwent a series of treatments to induce modifications. Laser and ion irradiations were performed using a pulsed laser, a continuous Ar beam, and a pulsed C beam. In addition, thermal annealing in vacuum was performed to examine the long-term effects of temperature. The composition of deposited film was investigated using Ion Beam Analysis, the morphology and the structure, and the effects of treatments on the films were studied using SEM and TEM microscopies and Raman spectroscopy. Changes in electrical resistance were also measured to explore potential applications of these films after treatment.

Figures (11)

• Figure 1: Deposition scheme with IBS setup and thermal evaporator
• Figure 2: RBS results on pure Co and Co - C$_{60}$ samples obtained with 2MeV $He^+$. Black dots are experimental data and the red line represents the fit obtained from SIMNRA simulation.
• Figure 3: SEM pictures taken at 50kX magnification of as deposited sample.
• Figure 4: Elemental mapping of particle on the as deposited sample.
• Figure 5: TEM micrograph of as prepared sample.