Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 71: New concepts and new materials

HL 71.2: Talk

Thursday, March 19, 2015, 10:30–10:45, EW 201

Coulomb blockade in metal nanoparticle field-effect
transistors — •Hauke Lehmann, Svenja Willing, Sandra Möller, Mirjam Volkmann, and Christian Klinke — Institut für Physikalische Chemie, Universität Hamburg, Grindelallee 117, 20146 Hamburg, Germany

Metallic nanoparticles offer possibilities to build and improve basic electrical devices. The role of a semiconductor’s bandgap is adopted by the Coulomb energy gap [1] due to the charging of the single particles’ capacities. Thus, it is required to keep the nanoparticles individualized by tunnel barriers, while a merging of the particles would render them metallic again.

We synthesize monodisperse CoPt nanoparticles by colloidal
chemistry [2]. Those particles are deposited via the Langmuir-Blodgett technique as highly-ordered homogeneous monolayers onto substrates with predefined gold electrodes. Additional structuring of the films yields stripes from individual nanoparticles. Such a defined channel can be controlled through a carefully adjusted gate voltage much more precisely compared to former experiments on whole nanoparticle films [3]. An insulating layer on top of the nanoparticles enables the application of a local top-gate electrode instead of using the global back gate. We find oscillations indicating the Coulomb blockade at temperatures of up to approximately 100 K.

[1] C. W. J. Beenakker, Phys. Rev. B 44, 1646 (1991)

[2] S. Lim et al., Nano Lett. 10, 964 (2010)

[3] Y. Cai et al., J. Appl. Phys. 114, 034311 (2013)