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

Abstract

It was confirmed that the hydrogen plays an important role in the direct formation of nano-sized crystalline silicon (nc-Si) during the deposition of amorphous silicon (a-Si) layers by electron cyclotron resonance chemical vapor deposition (ECR-CVD) on silicon and silicon-dioxide substrates. Two photoluminescence (PL) peaks, one at 680 nm and the other at 838 nm, were observed at room temperature from the samples. With respect to the substrate temperature during the deposition process and the post-annealing temperature, the relation between the hydrogen content and the intensities of the PL signals was comparable. The results of Raman spectroscopy and FTIR measurement 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.