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|Type:||Artigo de periódico|
|Title:||Microcrystalline Diamond Deposition On A Porous Silicon Host Matrix|
|Abstract:||Porous silicon (PS) is a nanostructured material obtained by etching pores into crystalline Si wafers. In this paper, we report on the nucleation and growth of diamond on very thick PS films (130-220 μm) of very high porosity (10-50%). The edges of the pores were in the form of small crosses, which followed the original directions of the 〈100〉c-Si. The diamond coating was made by chemical vapor deposition (CVD) in a hot-filament reactor. We observed that the diamond nucleation occurs mainly at the edges of the pores but relatively few nuclei follow a preferential orientation axis. As the nucleation density is very low, coalescence does not occur even after 11 h and 30 min of deposition. Using a pre-deposition `seeding' process with diamond grains, it was possible to produce a complete diamond CVD coating. A cross-section analysis of the diamond/PS/c-Si structure by scanning electron microscopy (SEM), micro-Raman and photoluminescence spectroscopies revealed interesting results: the luminescence of the PS under the diamond layer is preserved. There is no diamond deposition inside of the pores, but a small permeation of carbon was identified which forms diamond-like phases at the bottom of the pores. The Raman analyses indicated also a small contamination of the diamond layer by Si nano-crystals.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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