Structural evolution of nanocrystalline silicon studied by high resolution transmission electron microscopy

Abstract

In this work, nanocrystalline silicon (nc-Si) embedded in amorphous silicon nitride (a-SixNy) films have been characterized by High Resolution Transmission Electron Microscopy (HRTEM). The films have been grown by remote plasma enhanced chemical vapour deposition (RPECVD) onto silicon substrates using a mixture of SiCl 4 , NH 3 and H 2 . Subsequently, the sample has been introduced to an annealed process. The nanocrystalline inclusions have been measured from the analysis of HRTEM images. The size of nc-Si inclusions is modified due to the annealing process. The diameter of nc-Si inclusions in as-grown films vary from 1.3 to 3.1 nm. In annealed films, a high density of new clusters with reduction of 1 nm of those diameters is observed, as well as the coalescence phenomenon among some nc-Si inclusions is observed too. Consequently, the diameters of annealed films nc-Si inclusions range from 0.7 to 4 nm. The thin films show an excellent photoluminescence emission. The density per unit area and size of the nc-Si inclusions are correlated with the PL emissions. The influence of the structural changes of the nc-Si on the PL emissions is discussed.

SILICON QUANTUM DOTS GROWTH IN SiNx DIELECTRIC: A REVIEW

“…Reports of strong PL after postheat-treatment are attributed to the formation of Si-QD and hydrogen passivation of dangling bonds related to Si, N 2 at the interface of Si-QDs and Si 3 N 4 due to annealing in H 2 . 9, 16,23,25,30 In summary, the PL peak appearing in the blue region may be due to the defects or QCE of Si-QDs embedded in SiN x matrix. If a smooth variation in the PL peak due to Si-QD size variation is found, then it is definitely due to Si-QD QCE.…”

“…Reactive evaporation, 25 ion beam implantation 26 and different CVD techniques 4,9,[27][28][29][30][31][32][33][34] are used for deposition and post-deposition annealing of films containing Si-QDs in SiN x dielectric. High Si-QD density and better charge tunneling probability can be obtained in Si-QD/dielectric ML structure rather than in randomly dispersed Si-QDs in thick dielectric matrix.…”

Electronic Structure of Silicon Nanocrystals Passivated with Nitrogen and Chlorine

“…3,4,6,7 Si-nc embedded in chlorinated silicon nitride thin films have also been shown to have efficient photoluminescence in the red (1.8 eV) to blue-violet (3.1 eV) region, and this even improves with thermal annealing. 8,[12][13][14] Although in this case the Si-nc can be passivated with H, N, or Cl atoms, it has been previously speculated that their good photoluminescent properties are due to the passivation with N and/or Cl. 12,13 However, theoretical calculations are required to support the validity of this hypothesis.…”

Enhancement and quenching of photoluminescence from silicon quantum dots by silver nanoparticles in a totally integrated configuration

“…A high-purity silica glass plate (20×20×1 mm) with OH content less than 1 ppm and total impurity content less than 20 ppm, was implanted at room temperature with 1.5 MeV Si +2 ions at fluence of 1.3×10 17 ions/cm 2 , using the 3 MV Tandem accelerator (NEC 9SDH-2 Pelletron) facility at the Instituto de Física of the Universidad Nacional Autónoma de México (IFUNAM). After implantation, the sample was thermally annealed in a reducing atmosphere (50%N 2 + 50%H 2 ) at 1100…”

“…Besides, it has been well established that metallic nanoparticles, such as Ag and Au, support surface plasmon resonance (SPR), which can be tuned throughout the UV-vis-near-IR spectrum by controlling their shape, size and their local dielectric environment. [12][13][14][15] There are many ways to fabricate nanocrystalline silicon, such as plasma enhanced chemical vapor deposition (PECVD), remote-PECVD (RPECVD), 4,16,17 implantation. 6,18,19 In this work we have used the ion implantation technique to obtain a totally integrated configuration formed by Si QDs and silver nanoparticles (Ag NPs).…”