Quantum size effect from n-type porous silicon

N-type and p-type Porous Silicon (PSi) have been observed by Scanning Electron Micrograph (SEM) and characterised by Photoluminescence (PL). The porous n-type silicon obtained under illumination (photoelectrochemical etching), consists of a layer of nanoporous silicon which covers a macroporous silicon layer with pores in the micron size range. Compared with the p-type PSi, the room temperature visible luminescence is many times reduced in the case of n-type PSi, and there is a photoluminescence peak shift to higher wavelengths. This shows that the luminescence from porous silicon is caused by quantum size effect.