Single target sputter deposition of alloy nanoparticles with adjustable composition via a gas aggregation cluster source

Abstract

Alloy nanoparticles with variable compositions add a new dimension to nanoscience and have many applications. Here we suggest a novel approach for the fabrication of variable composition alloy nanoparticles that is based on a Haberland type gas aggregation cluster source with a custom-made multicomponent target for magnetron sputtering. The approach, which was demonstrated here for gold-rich AgAu nanoparticles, combines a narrow nanoparticle size distribution with in operando variation of composition via the gas pressure as well as highly efficient usage of target material. The latter is particularly attractive for precious metals. Varying argon pressure during deposition, we achieved in operando changes of AgAu alloy nanoparticle composition of more than 13 at%. The alloy nanoparticles were characterized by x-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy. The characteristic plasmon resonances of multilayer nanoparticle composites were analyzed by UV-vis spectroscopy. Tuning of the number of particles per unit area (particle densities) within individual layers showed an additional degree of freedom to tailor the optical properties of multilayer nanocomposites. By extension of this technique to more complex systems, the presented results are expected to encourage and simplify further research based on plasmonic multi-element nanoparticles. The present method is by no means restricted to plasmonics or nanoparticle based applications, but is also highly relevant for conventional magnetron sputtering of alloys and can be extended to in operando control of alloy concentration by magnetic field.

Nucleation and Growth of Magnetron‐Sputtered Ag Nanoparticles as Witnessed by Time‐Resolved Small Angle X‐Ray Scattering

“…The employment of highly nonequilibrium conditions favors tailoring the morphology of resultant NPs which strongly depends on the rate with which NPs equilibrate themselves with the ambient gas . Furthermore, mixing of two or more metals can be realized either simultaneously or sequentially giving rise to a wealth of homogeneous or heterogeneous nanoalloys, unattainable by conventional means . Despite great progress in laboratory synthesis of novel NPs with advanced functionalities, commercial applications of magnetron‐sputtered NPs are still far from being at hand.…”

“…[2][3][4][5] Furthermore, mixing of two or more metals can be realized either simultaneously or sequentially giving rise to a wealth of homogeneous or heterogeneous nanoalloys, unattainable by conventional means. [6][7][8][9][10][11][12][13][14][15][16][17][18] Despite great progress in laboratory synthesis of novel NPs with advanced functionalities, commercial applications of magnetron-sputtered NPs are still far from being at hand. A major obstacle for the commercialization is commonly seen in the uncompetitively low rate of the NP deposition on surfaces which is related to a generally recognized issue of the loss of the NPs inside the aggregation chamber before they leave it.…”

Magnetron-sputtered copper nanoparticles: lost in gas aggregation and found by in situ X-ray scattering

“…The method has acquired particular popularity as is evidenced by an increasing number of papers that have been published in recent years. Single-metal, [4][5][6][7][8][9][10][11][12][13][14][15] alloyed [16][17][18][19][20][21][22][23][24][25][26] and heterostructured NPs [27][28][29][30][31][32][33][34][35][36][37][38][39][40] have been successfully synthesized.…”

Cluster‐Assembled Nanocomposites: Functional Properties by Design

“…[18] However, the formation of the multiple-phase nanocomposite microstructure is essentially dependent on the immiscibility of the materials being deposited. [12,22] Today's cluster ion beam technology offers a great degree of control over the fabrication of clusters with defined size, size distribution, and chemical composition. Furthermore, the control over the size and size distribution of the secondary nanophase is limited.…”

“…[21] The simultaneous deposition of preformed clusters with a molecular beam of another element/compound/alloy (matrix material) onto a substrate offers a way to overcome the aforementioned limitations. [12,22] Today's cluster ion beam technology offers a great degree of control over the fabrication of clusters with defined size, size distribution, and chemical composition. Moreover, the possibility to explore several deposition scenarios with variable cluster impact energies onto substrates can lead to the potential control of the morphology of the clusters.…”