Mixed-dimensional InAs nanowire on layered molybdenum disulfide heterostructures selective-area van der Waals epitaxy.

Self-assembly of vertically aligned III-V semiconductor nanowires (NWs) on two-dimensional (2D) van der Waals (vdW) nanomaterials allows for integration of novel mixed-dimensional nanosystems with unique properties for optoelectronic and nanoelectronic device applications. Here, selective-area vdW epitaxy (SA-vdWE) of InAs NWs on isolated 2D molybdenum disulfide (MoS) domains is reported for the first time. The MOCVD growth parameter space (, V/III ratio, growth temperature, and total molar flow rates of metalorganic and hydride precursors) is explored to achieve pattern-free positioning of single NWs on isolated multi-layer MoS micro-plates with one-to-one NW-to-MoS domain placement.

Black GaAs with Sub-Wavelength Nanostructures Fabricated via Lithography-Free Metal-Assisted Chemical Etching.

A practical nanofabrication process is detailed here for the generation of black GaAs. Discontinuous thin films of Au nanoparticles are electrodeposited onto GaAs substrates to catalyze site-specific etching in a solution of KMnO and HF according to the metal-assisted chemical etching mechanism. This provides a solution-based and lithography-free method for fabricating sub-wavelength nanostructure arrays that exhibit solar-weighted reflectance approaching 4 %.

Ordered Al GaAs Nanopillar Arrays via Inverse Metal-Assisted Chemical Etching.

The ternary III-V semiconductor compound, Al GaAs, is an important material that serves a central role within a variety of nanoelectronic, optoelectronic, and photovoltaic devices. With all of its uses, the material itself poses a host of fabrication difficulties stemming from conventional top-down processing, including standard wet-chemical etching and reactive-ion etching (RIE). Metal-assisted chemical etching (MacEtch) techniques provide low-cost and benchtop methods that combine many of the advantages of RIE and wet-chemical etching, without being hindered by many of their disadvantages.

Fabrication of Suspended III-V Nanofoils by Inverse Metal-Assisted Chemical Etching of InGaP/GaAs Heteroepitaxial Films.

Metal-assisted chemical etching (MacEtch) has been established as a low-cost, benchtop, and versatile method for large-scale fabrication of semiconductor nanostructures and has been heralded as an alternative to conventional top-down approaches such as reactive-ion etching. However, extension of this technique to ternary III-V compound semiconductor alloys and heteroepitaxial systems has remained relatively unexplored. Here, Au-assisted and inverse-progression MacEtch (I-MacEtch) of the heteroepitaxial InGaP/GaAs material system is demonstrated, along with a method for fabricating suspended InGaP nanofoils of tunable thickness in solutions of hydrofluoric acid (HF) and hydrogen peroxide (HO).