Photoluminescence from SiO2/Si/SiO2structures

Abstract

Si layers were developed on pre-oxidized Si wafers by decomposition of silanein a low pressure chemical vapour deposition reactor. By keeping thedeposition time constant (2 min) three sets of samples were fabricated atdeposition temperatures equal to 580, 610 and 625 °C.The deposited Si layers were thinned by high temperature dryoxidation thus forming SiO2/Si/SiO2structures. Room temperature photoluminescence (PL) measurements showed that for thosesamples in which the thickness of the remaining Si layer was greater than ∼ 6 nm,the spectra exhibited a peak at ∼ 650 nm.Prolonged oxidations led to the formation of SiO2/nanocrystalline-Si/SiO2structures in which the thickness of the remaining nanocrystalline Si (nc-Si) layerwas smaller than 3 nm. The PL spectra obtained from these structures were atleast ten times stronger compared to the previous ones. The PL peakwavelength exhibited a weak dependence on the nc-Si layer thicknessshifting from 800 to 720 nm for nc-Si thickness decreasing from ∼ 3 to ∼ 0.5 nm.In this publication we present our experimental findings, which indicate that theintensity of the 720–800 nm PL band is influenced by the deposition temperatureof the initial Si layer and by the thickness of the oxide layer between the nc-Silayer and the Si substrate.