CLASSIFICATION OF THE PORE STRUCTURE OF N-TYPE SILICON AND ITS MICROSTRUCTURE

Porous silicon samples were grown under various anodization conditions on {100} oriented n-silicon substrates. Scanning and transmission ele ctron microscope observations have shown that the microstructure of po rous silicon primarily falls into three categories, which can be class ified as single layer, double layer, and large macropore types. These three types differ not only in their microstructural details, but also in luminescence properties. In all three types of samples, the inner surface of pores created by anodization is coated with a low density a morphous material, which contained silicon and oxygen. In addition, al l the pore surfaces were roughened by anodization, leaving nanoscale c rystalline silicon asperities.