Structural changes in porous silicon during annealing

Porous silicon can be used as separation layers in layer transfer technology where a thin layer of crystalline silicon is separated from a large wafer and transferred onto a cheap foreign substrate. The porous layers are part of the fabrication process and undergo the processing treatment, especially the thermal treatments. We have analyzed by transmission electron microscopy the structural development of porous silicon layers in dependency of annealing and layer preparation conditions. The fabrication of solar cells by layer transfer technology is based on double layers and we used in addition single layers for evaluating the details of structural changes. We can explain the structural development during annealing by means of the classical sintering theory.