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 (photoelectroch emical etching), consists of a layer of nanoporous silicon which cover s a macroporous silicon layer with pores in the micron size range. Com pared with the p-type PSi, the room temperature visible luminescence i s many times reduced in the case of n-type PSi, and there is a photolu minescence peak shift to higher wavelengths. This shows that the lumin escence from porous silicon is caused by quantum size effect. 1998 Pub lished by Elsevier Science B.V. All rights reserved.