Large Scale Self-Organization of 2D Hexagonal Ge and Au Nanodots on Patterned TiO2 for Optoelectronic Applications

Abstract

We report a new strategy for the ordering of 2D arrays of Ge and Au nanodots on a silicon wafer using a patterned titanium oxide layer. In a rst step, a TiO 2 layer is prepared by block-copolymer-micelles-assisted sol-gel deposition on a full Si wafer, followed by a thermal annealing. The process leads to hexagonally positioned perforations of homogeneous size and spacing. In a second step, these TiO 2 Inorganic NanoPatterns (INPs) are used as templates for the organization of Ge and Au nanodots. Germanium adatoms deposited by Molecular Beam Epitaxy on INPs, diuse and self-assemble into nanodots, located within the INPs pores. They form homogeneous sub-20 nm Ge nanodots in epitaxy on the silicon substrate and regularly distributed with one dot per perforation. The same approach is used for the formation of Au nanodots. In this case, a gentle mechanical polishing is requiered to suppress the dots seating at 1 the top of the TiO 2 network. The process developed in this study paves the way to the large scale self-organisation of quantum dots that are highly interesting for various applications, such as opto-electronics, and microelectronics.