Formation of nano-structured thin silicon layers by hydrogen plasma treatment of monocrystalline silicon

Abstract

A technique for the production of nano-structured Si films using hydrogen plasma treatments of monocrystalline Si substrates has been developed. Nanostructured layers were studied by scanning electron microscopy (SEM), Raman spectroscopy and photoluminescence. With Raman spectroscopy, it was found that the nearly free H/sub 2/-molecules in nano-voids appear in hydrogen plasma treated silicon. These nanovoids filled by hydrogen molecules are stable up to 400/spl deg/C. It was established by SEM that the treated samples exhibit structures with the typical dimensions well below 100 nm. It is shown that the doping of such nano-structured layers by phosphorous can be done during the hydrogenation which leads to the formation of high conductive nano-structures. After the Ar laser irradiation in air the nano-structured silicon layers exhibit a broad photoluminescence (PL) in the visible spectral range, which can be attributed to the evolution of chemical structures and dimensions of Si based nano-clusters due to the laser assisted processes. The advantage of the proposed method is that there is no need for any deposition process in this case to produce a Si-based nano-structured layer. The possible applications of the silicon-based nano-structured layers by the proposed method are discussed.