Silicon-rich/silica multilayers: A means to provide a link between the excitonic 1D quantum confinement and the photoluminescence parameters

The photoluminescence properties—intensity I_PL, emission energy E_PL and decay lifetime τ_PL—of silicon-rich silicon oxide (SRSO)/silica (SO) multilayers are investigated as a function of the optical pump flux (φ) of an argon laser and the measurement temperature in four kinds of samples corresponding to different SRSO sublayer thicknesses (namely 0.7, 1.4, 3.3 and 4.5 nm). The excitons created by the incident laser light mainly within the SRSO layers or at the SRSO/silica interface are confined in the multilayer growth direction (normal to the layers). This so-called 1D exciton quantum confinement effect has been independently described by two models (the state filling, the electron-hole exchange interaction). It is shown in this paper that both models are complementary since we have been able to reproduce, on the one hand, flux dependence of main PL features (energy, intensity and lifetime) of all fabricated samples and on the other hand, the evolution of the singlet-triplet energy splitting as a function of the SRSO sublayer thickness.