Taming of Ga droplets on DLC layers—size tuning and local arrangement with nanometer accuracy

Abstract

A new method for the fabrication of spherical gallium nanoparticles (Ga-NPs) on diamond-like carbon (DLC) layers with high precision in their desired diameter and positioning is presented. The basic principle is the pre-patterning of a DLC film by focused Ga(+) ion beam irradiation and subsequent annealing. During thermal treatment the evolution of single Ga-NPs with spherical shape on irradiated areas is driven by phase separation and surface segregation of Ga from the supersaturated DLC layer. The shape and size of the implanted areas as well as the ion fluence serve as a Ga reservoir for the nanoparticle (NP) evolution which is strongly correlated with the NP diameter. For the formation of segregation seeds to avoid random segregation of the NPs small spots are additionally implanted with Ga within the irradiated areas. The NP evolution is then assessed with respect to the seed position and the material for the Ga-NP growth is gathered from the surrounding reservoir. Using this technique Ga-NPs were fabricated with a diameter ranging from 40 nm up to several hundred nm. Prospective applications, i.e. in the field of plasmonics, arise from the arrangement in chains as well as in periodical two-dimensional arrays with defined NP size and interparticle distance.

Nanostructures by Mass-Separated FIB

“…This precise correlation between the implanted area and the size of the single Ga-NP is shown in Fig. 19.30 [97].…”

“…19.23a. The spherical shape caused by the high surface tension of gallium opens the way to a defined production of gallium nanoparticles (Ga-NPs) by FIB implantation and subsequent annealing, once the tailoring of the particle's arrangement and their size can be mastered [97].…”

“…After annealing, the resulting structure is a two dimensional array of well-ordered Ga-NPs that are all equal in size, which is shown in Fig. 19.31a [97].…”

A review of plasma-assisted deposition methods for amorphous carbon thin and ultrathin films with a focus on the cathodic vacuum arc technique

“…Moreover, the conversion of the low-sp 3 surface layer of FCVA a-C films to graphene is desirable because it enhances the tribological properties [257,258]. In a completely different application involving thermal treatment, Ga nanospheres were formed at the surface of FCVA a-C films implanted with Ga after thermal annealing at 500 °C for 1 h in vacuum, which has important applications in photonics [259]. This phenomenon was attributed to Ga supersaturation of the a-C matrix, resulting in surface segregation of the Ga during annealing.…”

In situ transmission electron microscopy studies of the kinetics of Pt-Mo alloy diffusion in ZrB2 thin films

“…Previous studies have shown that FIBinduced Ga segregates onto the surface in the form of spherical droplets. [24][25][26][27][28][29] Within an hour of annealing at T a $ 773 K, most of the smaller Ga droplets disappear from the transparent regions of the sample via Ostwald ripening and are absorbed by larger droplets located at the thicker ends of the sample. 30 In situ annealing at higher temperatures T a between 1073 and 1173 K are carried out in the double C s -corrected Link€ oping FEI 80-300 Titan 3 scanning TEM (STEM) equipped with EDS and EELS spectrometers.…”