A Combination of Metal Assisted Photochemical and Photoelectrochemical Etching for Tailored Porosification of 4H SiC Substrates

Abstract

Porous 4H-SiC layers were prepared with a tailored sequence of metal assisted photochemical etching (MAPCE) and photoelectrochemical etching (PECE) steps. Porous layers resulting from MAPCE provided initiation sites for a subsequent PECE process. Finally, the porosity of the porous layers was increased to the desired degree with a second MAPCE step. By applying this sequence, the problem of skin and cap layer formation occurring during pure PECE is avoided. In addition, layers with a homogeneous porosity depth profile are obtained, which is not possible when only pure PECE is applied.