Formation of InP nanomembranes and nanowires under fast anodic etching of bulk substrates

Electrochemical nanostructuring of (111) oriented GaAs crystals: from porous structures to nanowires

A comparative study of the anodization processes occurring at the GaAs(111)A and GaAs(111)B surfaces exposed to electrochemical etching in neutral NaCl and acidic HNO₃ aqueous electrolytes is performed in galvanostatic and potentiostatic anodization modes. Anodization in NaCl electrolytes was found to result in the formation of porous structures with porosity controlled either by current under the galvanostatic anodization, or by the potential under the potentiostatic anodization. Possibilities to produce multilayer porous structures are demonstrated. At the same time, one-step anodization in a HNO₃ electrolyte is shown to lead to the formation of GaAs triangular shape nanowires with high aspect ratio (400 nm in diameter and 100 µm in length). The new data are compared to those previously obtained through anodizing GaAs(100) wafers in alkaline KOH electrolyte. An IR photodetector based on the GaAs nanowires is demonstrated.

Schottky Barriers Based on Nanoporous InP with Gold Nanoparticles

Schottky barrier structures based on nanoporous InP with inclusion of Au nanoparticles and evaporated semitransparent Au film have been made. The spectra of short-circuit photocurrent in the visible range and current-voltage characteristics have been measured. Prepared structures are characterized by increased photocurrent due to the microrelief interface and surface plasmon excitation in gold nanoparticles as well as increased surface recombination especially in the short wavelength region.

Inverse metal-assisted chemical etching produces smooth high aspect ratio InP nanostructures

Creating high aspect ratio (AR) nanostructures by top-down fabrication without surface damage remains challenging for III-V semiconductors. Here, we demonstrate uniform, array-based InP nanostructures with lateral dimensions as small as sub-20 nm and AR > 35 using inverse metal-assisted chemical etching (I-MacEtch) in hydrogen peroxide (H2O2) and sulfuric acid (H2SO4), a purely solution-based yet anisotropic etching method. The mechanism of I-MacEtch, in contrast to regular MacEtch, is explored through surface characterization. Unique to I-MacEtch, the sidewall etching profile is remarkably smooth, independent of metal pattern edge roughness. The capability of this simple method to create various InP nanostructures, including high AR fins, can potentially enable the aggressive scaling of InP based transistors and optoelectronic devices with better performance and at lower cost than conventional etching methods.