Peculiarities of the formation and properties of light-emitting structures based on ion-synthesized silicon nanocrystals in SiO2 and Al2O3 matrices

Abstract

A comprehensive comparative study of SiO 2 and Al 2 O 3 oxide layers with Si nanocrystals formed by Si + ion implantation and high temperature annealing has been performed. Information on morphology, phase composition, structure, and luminescent properties of ensembles of ion synthesized silicon nanocrys tals has been obtained using confocal Raman microscopy, X ray diffraction, Fourier transform infrared spec troscopy, electron paramagnetic resonance, and photoluminescence. It has been found that the peculiarities of the formation of nanocrystals, the distribution of nanocrystals over the depth of the implanted layer, the structure, and the character of chemical bonds are similar for both types of oxide matrices; however, the pho toluminescence in the wavelength range 600-1000 nm, which is caused by the nanocrystals in the Al 2 O 3 matrix, has been observed only in the case of the formation of SiO 2 shells around the Si nanocrystals. The surface oxidation of the Si nanocrystals, which is necessary for the formation of SiO 2 shells, is possible due to the presence of excess oxygen in the Al 2 O 3 matrix (the case of Si implantation into the deposited Al 2 O 3 film), as well as due to the inflow of oxygen from the annealing atmosphere (the case of Si implantation into sap phire). In order to verify the quantum confinement mechanism of luminescence, available data on the tem perature dependence of the photoluminescence intensity have been analyzed. An analysis of the mechanisms of charge transfer and electroluminescence excitation in diode structures based on thin ion synthesized layers with silicon nanocrystals has also been performed.

Si-rich Al2O3 films grown by RF magnetron sputtering: structural and photoluminescence properties versus annealing treatment

“…This indicates the Si-nc in sapphire are under the compressive stress [13]. In contrast in our samples, the ω ТО-Si-nc is shifted to the lower wavenumbers (below 519 cm −1 ).…”

“…It is worth to note that the ω ТО-Si-nc for the Si-nc formed in sapphire at 700°C to 1,050°C is observed in the range from 520 to 525 cm −1 [13] and is shifted to the higher-energy side with respect to peak position of intrinsic c-Si. This indicates the Si-nc in sapphire are under the compressive stress [13].…”

“…Thus, this emission can be ascribed to the defects located near Si-nc/host interface (i.e., in the shell that covered these Si-ncs). This shell can consist of both alumina and silica [13,16]. …”

“…Most known methods are Si ion implantation [13,14] and electron beam evaporation followed by subsequent high-temperature annealing as well as laser ablation [15]. For these systems, the successful Si-nc formation was already demonstrated.…”

Correlation of size and oxygen bonding at the interface of Si nanocrystal in Si–SiO2 nanocomposite: A Raman mapping study

“…Different types of insulating materials, especially SiO 2 , have been used to grow multilayer structure (Si/SiO 2 ), because multilayer structure can overcome the Shockley‐Queisser limit of 30% efficiency . Irrespective of growth technique used, variation in Si phonon wavenumbers in the range 495–519 cm −1 in Si–SiO 2 NCp is reported in the literature . Various groups have reported different Si phonon wavenumbers in the range noted in the preceding texts, using different excitations for Si–SiO 2 NCps.…”