Fabrication of germanium nanodisk array by neutral beam etching with protein as etching mask

Abstract

A uniform 10 nm diameter Ge two-dimensional (2D) nanodisk array structure was fabricated using iron oxide cores in a 2D closed-packed array of cage shaped proteins, ferritins, as an etching mask. Thin Ge layer on Si substrate was protected by a-Si capping layer and etched, which eliminated an uncontrollable factor of Ge native oxide. The density of Ge nanodisks was as high as 5.8 × 1011 cm−2, and the center-to-center distance was estimated to be 14 nm. It was demonstrated that a quantum confinement effect can be obtained with our fabricated Ge nanodisk array by controlling the nanodisk thickness. The obtained high density Ge nanodisk is promising for Ge/Si quantum dot intermediate band solar cells and other photonics devices.

Viral‐based nanomaterials for plasmonic and photonic materials and devices

“…Ferritin protein cages present an appealing alternative to viral capsids in the production of SSSCs and DSSCs. Germanium quantum dot intermediate band SSSCs (QD-IBSSSCs) can be fabricated using ferritin-coated iron-oxide NPs, or MF (Fujii et al, 2017). To produce arrays of Ge QDs, MFs were layered on the substrate and served as an etching mask for neutral beam etching.…”

Low-temperature InGaAs oxidation using oxygen neutral beam

“…[17][18][19] A bio-nanotop-down process of good uniformity and high in-plane density requires a highly reliable oxide layer. In our previous studies, [20][21][22][23][24][25][26][27] we fabricated a high-in-plane-density array consisting of ferritin molecules of group IV materials such as Si, Ge, and SiGe. The array contained a GaAs surface that was prepared by neutral beam oxidation (NBO) while forming a ferritin array with low in-plane density and disordered thermal silicon oxide.…”