Dresden 2003 – scientific programme

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HL: Halbleiterphysik

HL 52: Hauptvortrag Thonke

HL 52.1: Invited Talk

Friday, March 28, 2003, 11:00–11:45, POT/81

Polymer-defined semiconductor nanostructures — •Klaus Thonke — Abteilung Halbleiterphysik, Univ. Ulm, D-89069 Ulm

Semiconductor nanostructures with sizes down to a few nanometers can be defined in different, highly parallel processes with the aid of polymers. In a "top-down" approach, either micelles formed by diblock-copolymers or other self-assembled patterns like "breath figures" or imprints of colloids in polymer films are used for the formation of metal masks of different sizes on semiconductors in a first preparation step. These metal masks are then used in a highly anisotropic dry-etching process for the shaping of pillars in the semiconductor material. After additional evaporation and etching steps, dense patterns of nano-holes in metal films can be produced.

In a "bottom-up" approach, micelles act as nano-reactors for the formation of metal clusters of Zn, Cd, Mg or Cu which then can be oxidized so as to form to nanocrystals of the oxidic semiconductors ZnO, CdO, MgO, CuO etc.. When Au salts are added to the micelles, the resulting Au dots can be used as catalysts for the growth of ZnO nanopillars with high aspect ratio. Even ring-shaped (Zn,Cd)O semiconductor patterns can be formed starting with nanoporous polymer membranes, which are loaded by appropriate metal salts and then removed in an oxygen plasma, leaving "donut"-like (Zn,Cd)O rings.

Structural and optical properties of these nanostructures are discussed.