Formation of microporous silicon in straight macropore on n-type silicon under front side illumination

Abstract

To find a sacrificed layer on walls of silicon macropore, the microporous silicon (MPS) was formed on the wall of straight silicon macropore (SSMP) by electrochemical etching on n-type silicon. The front side illumination was used to control the thickness of MPS on SSMP wall. The experiment showed that the thickness of MPS was more easily controlled by changing the illumination than the applied electric field and etching electrolyte. So the injected carrier model (ICM) was proposed for deducing an experimental equation between the illuminance and MPS thickness. Light attenuation in silicon was confirmed as the major cause of MPS formation in SSMP. ICM model could be used to predict the porous structure etched by front side illumination on n-type silicon.