## 1 Introduction  
In the past, many efforts have been devoted to the fabrication of light emitting films that are compatible with silicon technology [1]. One of the proposed approaches is to use dielectric matrices with silicon nanocrystals (Si-NCs) or nano-agglomerates as active media. Among several other techniques, chemical methods have been used to fabricate such materials [2; 3; 4; 5; 6; 7; 8; 9; 10]. The origin of the photoluminescence (PL) of Si-NCs embedded into oxide films is still controversial [11], but there are two principal models commonly used to explain the emission mechanism. One is known as the Quantum Confinement Effect (QCE), in which the radiative process is carried out by electron-hole recombination in the Si-NCs; silicon nanocrystals below 5 nm show an effect of a quasi-direct bandgap due to the boundary conditions [6; 8; 12; 13]. The second model proposes the formation of defect-statesat the Si-NCs/SiO\({}_{2}\) interface where radiative recombination occurs [10; 14; 15]. In the literature, there is enough evidence of SiO\({}_{2}\) defects with specific emissions that simultaneous experiments of luminescence and detection of defects have been done during the years to link them. Just to mention a few, electron paramagnetic resonance (EPR), time resolved photoluminescence, and tunable laser excitation are some of the techniques used [16; 17; 18].  
Two main different emissive films of this kind have been proposed: those that produce centers with luminescent characteristics as they are synthetized; and films where Si-NCs are obtained separately from the dielectric matrix. In the first method, temperatures of around 1100 \({}^{\circ}\)C are needed to promote the nucleation and activation of radiative Si nanopoints, crystalline or not [3; 4; 19; 20]. Examples of these materials are the silicon rich oxides obtained by chemical vapor deposition (CVD), Ionic implantation of Si in a dielectric matrix, and thermally treated chemical solutions [4; 21; 22; 23]. These kind of silicon rich oxides show photoluminescence mainly in a range from 650 to 950 nm. However, if high energy is used to stimulate them, the range emission can be extended to the blue side of the electromagnetic spectrum. However, the high temperature annealing usually needed to promote the silicon-emissive center formation [3; 4; 19; 20] complicates their potential incorporation in CMOS (complementary metal-oxide-semiconductor) integrated circuits.  
On the other hand, Si-NCs obtained separately by a variety of techniques and mixed with SiO\({}_{2}\) solutions, such as Spin on Glass (SOG), have been of particular research interest because they are usually easy and low cost methods that do not need to be thermal treated to produce emissive films. In most of the cases, it has been reported that such films contain embedded Si-NCs embedded in the dielectric matrix. Their characteristic photoluminescence is rather on the blue side of the spectrum, varying with the diameter of the nanocrystals. Nevertheless, it has been reported that the emission depends on many factors, including the density of Si-NCs in the SOG, the way they are obtained and mixed, and the type and temperature used if they are annealed [24; 25; 26; 27]. Then, despite the existence of several studies, much research is still to be done in order to fully understand the luminescence mechanisms, and the optimal technological conditions to obtain reliable highly emissive films.  
In this work, in order to corroborate the chemical interaction between the Si-NCs and the SOG film, two different films are proposed: Si-NCs coated with a thin layer of SOG and Si-NCs embedded into the SOG film--hereafter, respectively referred to as \"coated\" and \"embedded\" films. Moreover, the coated and embedded films were studied with and without thermal annealing at 1100 \({}^{\circ}\)C to look deeply into its effects.