Analysis of layer structure variation of periodic porous silicon multilayer

Structures of periodic porous silicon multilayer, which were formed by the current density modulation method, were investigated by cross-sectional scanning electron microscopy (SEM) observation. When the layers were formed with a current density of 20 mA/cm(2) or less the thickness of the layers was constant regardless of the stack position of the layer. When the layers were formed with a current density of 50 mA/cm(2) or more, the thickness of the layers decreased and the porosity of the layers increased as the stack position of the layer became deep. The layer peeled off when the porosity of the layer increased up to aproximately 100%. The thickness variation of the layers and the peeling were prevented by raising the temperature of the electrolyte.