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The low-temperature (25–600 °C) oxidation of amorphous silicon boron alloy (a-Si:B) prepared by low-pressure chemical-vapor deposition, with varying boron contents (0%–25%), has been qualitatively studied using x-ray photoelectron spectroscopy. The oxidation of these amorphous a-Si:B films has been compared to that of crystalline silicon (c-Si) and boron (c-B). It was found that higher boron concentration in the Si:B alloy caused faster oxidation of both the Si and B components in the amorphous alloy as compared to either c-Si or c-B. At room temperature, suboxides were formed (Si+, Si2+, Si3+, B+, B2+) as opposed to oxides (Si4+, B3+). At higher temperature the oxidation was faster, as expected. In addition, at higher temperatures the SiO2 and B2O3 oxides were preferentially formed by the conversion of the suboxides. All the evidence suggests that the availability of three-coordinated B bonds in the Si:B alloy accelerates the oxidation process when compared to the oxidation of the tightly bounded c-Si or c-B.

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Thin films of an amorphous Si-B alloy with B contents 1–50% were deposited by low pressure chemical vapor deposition (LPCVD) from diborane (B2H6) and silane (SilH4) gases. XRD patterns of the as deposited films showed them to be completely amorphous. The films were annealed in N2 at 600–800°C for 30 minutes and characterized by Raman spectroscopy. Wet oxidation of the film was carried out 700°C for 30 minutes, and the films examined by XRD. The structural changes induced by B in the a-Si network discussed in the conceptual framework of the continuous random network (CRN) model. We conclude that the boron incorporation enhances the structural disorder and induces topological changes in the amorphous network.