2 WAYS OF POROUS SI PHOTOLUMINESCENCE EXCITATION

The mechanism of photoluminescence excitation (PLE) in porous silicon (PS) is studied. The investigation of the PS aging process by photolum inescence (PL), PLE, EPR, Auger, FTIR and SIMS methods show that two P LE bands correspond to different substances on a silicon wire surface. One of them is the species which is desorbed during aging with an act ivation energy approximate to 0.5-0.6 eV. The energy transfer from thi s species (absorption centers) to luminescence centers which may be lo cated in Si wire, Si/SiO interface or silicon oxide, is supposed. The nature of this species is discussed. The second substance is silicon o xide, probably. (C) 1998 Elsevier Science S.A. All rights reserved.