Role of hydrogen in the photoluminescence and the formation of nanocrystalline silicon

It was confirmed that the hydrogen plays an important role in the direct fo rmation of nano-sized crystalline silicon (nc-Si) during the deposition of amorphous silicon (a-Si) layers by electron cyclotron resonance chemical va por deposition (ECR-CVD) on silicon and silicon-dioxide substrates. Two pho toluminescence (PL) peaks, one at 680 nm and the other at 838 nm, were obse rved at room temperature from the samples. With respect to the substrate te mperature during the deposition process and the post-annealing temperature, the relation between the hydrogen content and the intensities of the PL si gnals was comparable. The results of Raman spectroscopy and FTIR measuremen t show that the phase of the deposited films varied from nc-Si to a-Si with increasing deposition temperature. That is, the crystalline phase changed to the amorphous phase with decreasing hydrogen content.