Nanostructurale nature of the porous GaAs layer formed on p+-GaAs substrate by electrochemical anodization
A porous GaAs layer has been formed by electrochemical anodization in HF based solution on extremely doped p-type GaAs substrate. Porous nature of the elaborated sample has been evidenced by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Nanostructurale nature of the porous layer has been demonstrated by X-ray diffraction analysis (XRD) and confirmed by photoluminescence spectroscopy (PL).
Mesoporous GaAs double layers for layer transfer processes
Mesoporous GaAs double layers with different porosities and thicknesses up to 7 µm are formed on highly doped p‐type 4 inch GaAs substrates by means of electrochemical etching in highly concentrated hydrofluoric acid electrolytes. Small 〈111〉 oriented pyramids form at the interface between porous layer and substrate if etching current densities below 7.5 mA cm−2 are applied. Porous double layers with different porosities are obtained by varying simultaneously the etching current density and the electrolyte concentration. The porosity of the porous GaAs layers decreases nearly linearly from 69 to 53% with electrolyte concentrations increasing from 30 to 50 wt.%, respectively. The etching process increases the mean roughness of the porous layer surface from 0.15 to 0.24 nm.
Direct observation of porous SiC formed by anodization in HF
A process for forming porous SiC from single‐crystal SiC wafers has been demonstrated. Porous SiC can be fabricated by anodizing n‐type 6H‐SiC in HF under UV illumination. Transmission electron microscopy reveals pores of sizes 10–30 nm with interpore spacings ranging from ≊5 to 150 nm. This is the first reported direct observation of porous SiC formation.