Direct formation of nanocrystalline silicon by electron cyclotron resonance chemical vapor deposition

We have confirmed the direct formation of nanosized crystalline silicon during the deposition of amorphous silicon layers by electron cyclotron resonance chemical vapor deposition (ECRCVD) on silicon and silicon-dioxide substrates. Two photoluminescence (PL) peaks at 680 and 838 nm were observed at room temperature from the samples. From cross-sectional high-resolution transmission electron microscopy (HRTEM) measurements, it was confirmed that nanosize silicon crystallites of 3-5 nm in diameter were randomly distributed throughout the amorphous silicon layer. Theoretical calculations using quantum size effects gave an average crystalline size of 4 nm which was consistent with the PL peak energy at 680 nm obtained from the sample. Also, the size of the crystallites could be controlled by the change of the substrate temperature during the deposition process.