The production of novel electronic materials and devices from metallic nanoparticle building blocks

Jeffery David Bielefeld, Purdue University

Abstract

Techniques for producing electronic devices of smaller and smaller dimensions are currently a major area of electronics research. The ultimate goal of nanoelectronics, however, is not just to build smaller versions of current electronic devices, but to exploit new phenomena. Nanometer-size metal particles are investigated in the present study as building blocks for novel electronic materials with novel physical properties. Metal nanoparticles are grown as aerosol particles in a unique gas aggregation reactor. The Multiple Expansion Cluster Source (MECS) can produce nanoparticles (or clusters) with mean diameters in the 1-10 nm range with a narrow size distribution. Cluster-based thin films are formed either from clusters deposited directly onto a substrate in a vacuum chamber or from clusters stabilized as colloidal particles in an organic solvent and cast onto the substrate. Colloidal stabilization is achieved by the formation of a self-assembled monolayer of alkanethiol surfactant molecules on the surface of each cluster produced in the MECS. Vacuum deposition of bare metal clusters is investigated as an alternative technique for producing metal interconnect lines. The film growth process and the electrical transport properties of such cluster-based metal interconnects is compared with those of conventional atomically deposited interconnects. The resistance of cluster-based interconnects to electromigration damage at high current densities is also investigated and is found to be superior to that of atomically deposited interconnects. Casting of colloidal metal clusters onto a flat substrate is investigated as a way of producing novel thin films that conduct electricity by single electron tunneling. When cast on a flat substrate (MoS$\sb2$, HOPG, SiO$\sb2$), the nanometer size clusters group to form close-packed monolayer arrays. The effects of substrate material, colloid concentration, and chemical annealing on the quality of these arrays is studied. Electronically-linked networks of gold clusters are synthesized, and initial measurements of their electrical conductivity are made.

Degree

Ph.D.

Advisors

Andres, Purdue University.

Subject Area

Chemical engineering|Materials science

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