Synthesis of Cubic and Hexagonal CdTe Nanoparticles Dispersed in SiO₂ Films: Role of Oxygen during Sintering

Abstract

Cadmium telluride nanoparticles dispersed in SiO2 films have been grown by the co-sputtering of elemental Cd, Te and SiO2 targets in argon atmosphere. The role of oxygen during annealing on the structural and optical properties of CdTe nanoparticles dispersed in SiO2 films has been studied. Formation of a CdTeO3 layer around the CdTe nanoparticle core due to ambient oxygen present in air results in structural defects and thus the formation of hexagonal CdTe nanoparticles in air-annealed samples. In vacuum-annealed samples, defect free and well-crystallized cubic CdTe nanoparticles are formed which show excitonic features in the absorption spectra. These results have been confirmed by carrying out i) annealing in vacuum and air ambiences in a sequence on the same sample and ii) by depositing an additional layer of SiO2 on the CdTe:SiO2 samples to prevent the diffusion of ambient oxygen.

Postsynthesis Crystallinity Improvement of Colloidal CdTe Nanoparticles Using Rapid Thermal Annealing

“…TEM was taken on all other temperature samples, and the size of the NPs remained constant. This finding is in contrast to an earlier finding by Dayal et al, wherein furnace-annealed CdTe NPs dispersed in SiO2 film grew in size . Similarly, in another study, the size of aqueous grown CdTe NPs was also seen to increase with higher annealing temperatures, according to Bandaranyake et al, in a conventional annealing environment .…”

“…This finding is in contrast to an earlier finding by Dayal et al, wherein furnace-annealed CdTe NPs dispersed in SiO2 film grew in size. 29 Similarly, in another study, the size of aqueous grown CdTe NPs was also seen to increase with higher annealing temperatures, according to Bandaranyake et al, in a conventional annealing environment. 30 The fact that, under the RTA process, these CdTe NPs retain their initial size offers advantages for incorporating NP implementation into optoelectronic devices.…”

Post-Synthesis Crystallinity Tailoring of Water-Soluble Polymer Encapsulated CdTe Nanoparticles using Rapid Thermal Annealing

“…TEM was taken on all other temperature samples and the size of the NPs remained constant. This finding is in contrast to an earlier finding by Mehta et.al, wherein furnace annealed CdTe NPs dispersed in SiO2 film grew in size [14]. Similarily, in another study, the size of aqueous grown CdTe NPs was also seen to increase with higher annealing temperatures according to Bandaranyake et.…”

Room temperature photoluminescence of CdTe nanocrystals embedded in a SiO2 matrix deposited on silicon by reactive rf sputtering

“…[6][7][8] Synthesis of nanostructures has been done using almost all the techniques available to materials science, among which many include processes that are not easily compatible with the technology of silicon devices. 22,23 We report here an alternative approach to produce, in a single step, CdTe nanoparticles with emission of light at room temperature. 9,10 These materials have attracted interest due to the possibility to apply them in the fabrication of solar cells with efficiency larger than 40%, 11,12 optical filters, optical sensors, waveguides, and in optical switching.…”