The effect of thermal annealing on the photoluminescence around 2.2-2.9 eV in hydrogenated amorphous silicon oxynitride films was investigated. The luminescence intensity increases monotonically with an increase in the annealing temperature for the samples with lower nitrogen contents (N/O = 0.06, 0.10 and 0.12). It shows a similar increase up to 500°C, while it decreases abruptly above 500°C for the samples with higher nitrogen contents (N/O = 0.14 and 0.18). The density of silicon dangling bonds depends on the annealing temperature in a manner opposite to that of the luminescence intensity in all the temperature region. Based on this correlation, it is thought that the silicon dangling bonds act as the quenching centre. Infrared absorption spectroscopy indicated that the precursor of silicon dangling bonds was the Si-H bond. Hydrogen was released at temperatures above 500°C from Si-H bonds, resulting in a large number of silicon dangling bonds that quench the luminescence.
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