Effects of Si-rich oxide layer stoichiometry on the structural and optical properties of Si QD/SiO₂multilayer films

Abstract

The effects of the stoichiometry of the Si-rich oxide (SRO) layer, O/Si ratio, on the structural and optical properties of SRO/SiO2 multilayer films were investigated in this work. SRO/SiO2 multilayer films with different O/Si ratios were grown by a co-sputtering technique, and Si quantum dots (QDs) were formed with post-deposition annealing. By transmission electron microscopy (TEM) and glancing incidence x-ray diffraction (GIXRD), it was found that the Si QD size decreases with increases in O/Si ratio. The photoluminescence (PL) spectrum varies with the O/Si ratio in band position, shape and intensity. In addition, it was observed that the absorption edge blue-shifts with increases in the O/Si ratio. The change in the absorption edge is consistent with strengthening quantum confinement effects in Si QDs, as indicated by TEM and GIXRD. The optical properties were also investigated by 2D photoluminescence excitation (2D-PLE) and lifetime measurements. The origin of emission and absorption is discussed based on the absorption, PL, 2D-PLE and decay time measurements.

Luminescent Devices Based on Silicon-Rich Dielectric Materials

“…At forward bias (FB) (positive voltage to FTO contact respect to Si substrate), the SRN-LEC shows a broad spectrum with the maximum emission centered at around 580 nm, and it remains at the same wavelengths for diferent voltages as shown in Figure 7(a). This luminescence has been reported as a characteristic behavior of defect-related EL [67]. In fact, the luminescent properties of SRN ilms in this chapter are related to the presence of defects.…”

“…Nevertheless, when the silicon content is increased (M20), the PL band appears mainly at the red side of the spectrum. The redshift of the main PL peak (after thermal annealing) has been widely observed and ascribed to the agglomeration of silicon excess and a subsequent silicon nanoparticle formation as a result of thermal annealing process [67][68][69][70][71]. Nevertheless, some point defects are also present within the SRO ilms.…”

“…It is widely accepted that violet-blue (400-460 nm), green (520), and even red (630) emission bands, obtained from the deconvolution of the PL spectrum [72], can be related with oxygen [46]. defect centers (ODC), E' δ (SiSi=Si) and NBOHC defects, respectively [67][68][69][70][71]. The E' δ center is one of the at least four diferent E' centers [43], which comprises an unpaired spin delocalized over ive silicon atoms and suggest the presence of very small Si-nps in the ilms.…”

Химический и фазовый состав многослойных нанопериодических структур a-SiO-=SUB=-x-=/SUB=-/ZrO-=SUB=-2-=/SUB=-, подвергнутых высокотемпературному отжигу

“…Высокий коэффициент стехиометричности слоев МНС был получен за счет направленного введения молекулярного кислорода в рабочую камеру в процессе напыления -подхода, часто применяемого для управ-ления величиной x, в частности, в пленках SiO x [26,27]. Отметим, что ранее для отдельных слоев SiO x и МНС a-SiO x /SiO 2 использовались технологические режимы, Рис.…”

Blue, Green and Yellow Emissions at the Same Time from Mn-doped ZnS Microbelts

“…Among them, Mn-doped ZnS nanocrystals have been receiving much attention due to their promising application in optoelectronic devices [8]. A large number of Mn-doped ZnS nanocrystals with simple morphologies, such as thin film, nanowires, and nanorods have been prepared by various techniques [9][10][11]. The most reports of Mn-doped ZnS focused on the emission due to 4 T 1 → 6 A 1 transition within the 3d shell of Mn 2+ .…”