Modified Metal Assisted Photochemical Etching technique for SiC porosification

A modified technique based on the well-known Metal Assisted Photochemical Etching is proposed for SiC porosification. Three main components are used: an UV lamp with peak intensity at 254 nm, a voltage supply and an oxidizing solution based on HF and H
2
O
2
. The morpho-structural features of the porous samples are analyzed by SEM images, X-ray diffraction, X-ray reflectivity and photoluminescence measurements. Both cylindrical (predominant) and triangular pore shapes are resulted after porosification. A mean diameter of around 10 nm is confirmed by both SEM analysis and XRD measurements. A porosity degree of 30 % (XRD) and 38 % (XRR) is obtained. A near-band edge emission peak is shifted from 395 nm (~ 3.13 eV @ reference) to ~ 410 nm (~ 3.02 eV @ porous SiC) indicating a slight bandgap narrowing along with modification of surface states from the porous layer. A large green-yellowish emission with overlapping bands centered at 540 nm (~ 2.29 eV) and 610 nm (~ 2.03 eV) are resulted both at reference and porous SiC sample, with a higher reduction of intensity at SiC porous one because of the interface traps density.