Seminario: Phosphorus incorporation in silicon nanoclusters embedded in silicon oxide

Giovedì 31 ottobre 2013 ore 15.00, Edificio Fisica, Aula Seminari S3 (III piano)

Relatore: Michele Perego (CNR-IMM Lab MDM, Via Olivetti, 2, I-20041 Agrate Brianza (MB), Italy)

Abstract: The interest towards doping of semiconductor nanostructures has steadily increased over the last decade. However, deterministic doping of nanostructured materials has been shown to be a very difficult task, as the physical mechanisms involved in the process are significantly different from those in bulk materials and a clear understanding of the problem is still missing. Two dimensional (2D) arrays of Si nanocrystals (NCs) in SiO2 can be considered as an excellent template for fundamental studies on the evolution of dopant incorporation when the semiconductor size approaches the nanoscale. In this work we focused on dopant diffusion, segregation and incorporation in a single layer of previously formed Si NCs (diameter ~ 3.5 nm) in order to develop a scientific background that would allow to understand more complex non-equilibrium processes such as in-situ doping (i.e. doping before NCs formation) and dopant ion implantation. For all these reasons the introduction of the dopants has been performed by depositing a P delta-layer on top of the SiO2 films containing a 2D layer of Si NCs after the synthesis of the nanostructures. The P diffusion in SiO2 and its segregation at the NCs layer have been characterized by SIMS as a function of different annealing times and temperatures. A quantification of the experimental profiles was achieved by measurements of the total P dose by RBS and NRA analyses. The concentration profiles have been fitted by full rate equation numerical calculations able to reproduce P diffusion in oxide and P capture and release by NCs, extracting the associated thermal energy barriers. The results have been related to the NCs size, arrangement, crystal phase and stability extracted by TEM analysis. This approach provided valuable insights on the doping at the nanoscale and in principle could be also applied to investigate other nanostructures.

Ospite: Roberto Guerra

[Ultimo aggiornamento: 23/10/2013 18:00:14]