Patterning of sub-10-nm Ge islands on Si(100) by directed self-assembly

A process is reported for creating arbitrary patterns of sub-10-nm Ge islands on a Si(100) substrate by directed self-assembly. Carbon-based templates are created on Si substrates by electron-beam-induced deposition using high-resolution electron beam lithography. Ozone etching, followed by annealing in ultra-high vacuum, yields small $(<4nm)$ SiC nucleation sites for subsequently deposited Ge. Quantitative analysis of atomic force microscope images reveals templated Ge islands with mean diameter $d∼8nm$⁠, averaging $2000±500$ atoms per island, with controlled spacings as small as 35 nm, and 2 nm absolute positional accuracy. The $Ge∕Si$ nanostructures reported here may find use in end-of-scaling classical computing and single-electron devices and spin-based quantum computing architectures.