By means of ab-initio calculations we investigate the optical properties ofpure a-SiN$_x$ samples, with $x \in [0.4, 1.8]$, and samples embedding siliconnanoclusters (NCs) of diameter $0.5 \leq d \leq 1.0$ nm. In the pure samplesthe optical absorption gap and the radiative recombination rate vary accordingto the concentration of Si-N bonds. In the presence of NCs the radiative rateof the samples is barely affected, indicating that the intensephotoluminescence of experimental samples is mostly due to the matrix itselfrather than to the NCs. Besides, we evidence an important role of Si-N-Si bondsat the NC/matrix interface in the observed photoluminescence trend.
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机译：通过从头算计算，我们研究了纯a-SiN $ _x $样品的光学特性，其中$ x \ in [0.4，1.8] $，并且样品中嵌入了直径为$ 0.5 \ leq d \ leq 1.0 $的硅纳米簇（NC）纳米在纯样品中，光吸收隙和辐射复合率根据Si-N键的浓度而变化。在存在NC的情况下，样品的辐射速率几乎没有受到影响，这表明实验样品的强光致发光主要是由于基质本身而不是NC引起的。此外，我们证明了在NC /矩阵界面处的Si-N-Si键在观察到的光致发光趋势中的重要作用。
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