Fabrication and Characterization of Macroporous Silicon and its potential for solar cell application

First goal within this project is to develop a method to detach multiple thin macroporous layers from Czochralski grown silicon substrate on an area of 1cm². The electrochemical process used therefore has to be optimized. Cylindrical holes are etched into the substrate´s surface. In a depth of 20 to 30 µm - the thickness of the absorber layer (see figure) - the pore diameters are widened in order to create a defined breakage point. Afterwards the pore diameter is decreased again. The process repeats several times and potentially allows an optimal material use of the Si substrate. For further electrical and optical characterization of the absorber layers, the process shall be transferred to a larger area. The long term goal is to qualify the absorber layers as active material for thin film solar cells.