Structural Analysis by Infrared and X‐Ray Photoelectron Spectroscopy of Amorphous Silicon Produced by Plasma‐Deposition

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Abstract
We investigate by IR and XPS a series of amorphous films with incorporating a few atomic percent of H and N. The question of IR band assignment in is reviewed relative to the observed IR spectra. In the material with intermediate oxygen fraction , most hydrogen is incorporated as (here the symbol in parentheses corresponds to an atom back‐bonded to ). The hydrogen incorporation pattern gradually changes to and as increases and consists completely of Si‐OH groups for . The analysis of XPS spectra demonstrates that the composition of the films is inhomogeneous at a microscopic scale: the feature of Si 2p core‐level spectra originates mainly from and groups (e.g., silicon atoms with none and three‐bonded oxygen atoms, respectively). The existence of a segregated, oxygen‐rich phase is also supported by the peak frequency of Si‐O‐Si stretching vibration: it is 1030 cm−1 for , a higher value than that predicted for homogeneous oxides of the same composition. The relative volume occupied by the oxygen‐rich phase progressively expands as , at the expense of the silicon‐rich phase . The volume ratio of the environment increases smoothly without drastic changes in the microscopic structure, and is already dominant at .

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