The preparation of porous silicon carbide (SiC) layers with wet chemical etching methods from single crystalline SiC wafers is presented. In particular, photochemical and photoelectrochemical etching techniques are studied and evaluated for SiC.
Photochemical etching is achieved with the deposition of platinum electrodes on the surface of SiC and the subsequent exposure of the wafer to an etching solution. Both UV irradiation as well as an oxidant are necessary for etching. The resulting porous layers show light interference effects when investigated optically as well as a reorganization of the porous structure when exposed to high temperatures. Therefore, application scenarios of this approach could be in the field of pressure or optical sensors and are discussed.
Photoelectrochemical etching utilizes an external power source to initiate the formation of a porous layer. The homogeneity of the porous layers is increased by combining photoelectrochemical with photochemical etching. A possible application scenario of porous SiC multilayers in optical sensors is presented.