Structural and optical properties of silicon rich oxide films in graded-stoichiometric multilayers for optoelectronic devices

Abstract

Silicon nanocrystals (Si-ncs) are excellent candidates for the development of optoelectronic devices. Nevertheless, different strategies are still necessary to enhance their photo and electroluminescent properties by controlling their structural and compositional properties. In this work, the effect of the stoichiometry and structure on the optical properties of silicon rich oxide (SRO) films in a multilayered (ML) structure is studied. SRO MLs with silicon excess gradually increased towards the top and bottom and towards the center of the ML produced through the variation of the stoichiometry in each SRO layer were fabricated and confirmed by X-ray photoelectron spectroscopy. Si-ncs with three main sizes were observed by a transmission electron microscope, in agreement with the stoichiometric profile of each SRO layer. The presence of the three sized Si-ncs and some oxygen related defects enhances intense violet/blue and red photoluminescence (PL) bands. The SRO MLs were super-enriched with additional excess silicon by Si+ implantation, which enhanced the PL intensity. Oxygen-related defects and small Si-ncs (<2 nm) are mostly generated during ion implantation enhancing the violet/blue band to become comparable to the red band. The structural, compositional, and luminescent characteristics of the multilayers are the result of the contribution of the individual characteristics of each layer.

Monolithically Integrable Si-Compatible Light Sources

“…As it is reported in[37], Si-ncs are observed in SRO multilayers, and their size and density depend on the features of each layer (silicon excess, thickness, etc. ), in agreement with other reports on multilayers[27,34,38]. Table2summarizes the Si-nc features of M-LECs.…”

“…If the characteristics of each SRO film are preserved in a SRO ML structure, it is possible to improve the charge injection and luminescence properties of SRO-based LECs using the band-gap engineering by the Si-nc size modulation. Under this approach, the composition, structural, and PL emission characteristics of SRO MLs with gradual change of R 0 from 10 to 30, and conversely, have been studied [27]. The Si and O gradual composition profiles in the SRO 10-20-30 multilayered system have been confirmed by X-ray photoelectron spectroscopy (XPS).…”

Tailoring Structural, Chemical, and Photocatalytic Properties of ZnO@β-SiC Composites: The Effect of Annealing Temperature and Environment

“…In fact, this is corroborated by an additional component revealed in Si 2p peak fitting (see Figure c) related to the Si–O–Zn bond. , Looking at the XRD results in Figure , it appears that this new component in the above XPS results seems to be related to the zinc silicate phase. , Now the third component peaking at ∼532.48 eV for O 1s level reflects the existence of the Si–O–Si bond . Interestingly, the deconvolution of Si 2p in Figure c gives a component at ∼103.31 eV signifying the existence of SiO 2 . , The existence of SiO 2 is found to be important for understanding the dynamics behind the formation of the zinc silicate phase in the ZnO@β-SiC composites during high-temperature annealing in air, and it will be discussed in the following. Again, the peaks originating at ∼101.18 and 102.38 eV in Si 2p are found to be associated with β-SiC and zinc silicate phases, respectively.…”

Study of the Effect of Nitric Acid in Electrochemically Synthesized Silicon Nanocrystals: Tunability of Bright and Uniform Photoluminescence

“…Figure 4 shows the FTIR spectra of the PSi films. The higher oxygen concentration in the PSi2, PSi3, and PSi4 samples is clearly observed by the presence of a well-defined band at about 1072 cm −1 , with a shoulder at about 1160 cm −1 , and two minor bands at 460 cm −1 and 800 cm −1 , corresponding to Si-O bonding for the stretching (s), asymmetric stretching (as), rocking (r), and bending (b) vibration modes, respectively [50,51]. Indeed, the PSi2 and PSi3 samples which emit the highest PL exhibit the strongest O-related IR absorption bands.…”