Photo- and electroluminescence from nanocrystalline silicon single and multilayer structures

Single and multilayer structures of nanocrystalline silicon/silicon dioxide (nc-Si/SiO2 were fabricated by alternate sequences of low-pressure chemica l vapor deposition (LPCVD) of thin silicon layers and high temperature ther mal oxidation. Silicon was deposited at 580 degrees C and the obtained film s were initially amorphous. During the high-temperature oxidation step, cry stallization of the amorphous layer and simultaneous oxidation of the top l ayer was assured. The oxide thickness was controlled by controlling the oxi dation time. Multilayers with five to ten periods were fabricated, with nc- Si thickness between 1.5 and 15 nm, and SiO2 thickness between 5 and 10 nm. Photoluminescence (PL) and transmission electron microscopy (TEM) were use d to characterize the films. Nanocrystalline silicon layers of thickness be low 5 nm showed 10 to 15 times more intense PL than those from thicker laye rs (12-16 nm thick). Electroluminescence (EL) was also studied and results will be discussed. (C) 2000 Elsevier Science S.A. All rights reserved.