[en] Tb³⁺-doped SiN_x films (SiN_x:Tb³⁺) were prepared by plasma-enhanced chemical vapor deposition (PECVD) and ion-implantation. And the effects of the SiN_x substrates with different Si concentrations on the light emission of Tb³⁺ were investigated. Experimental results show that two groups of photoluminescence (PL) peaks of Tb³⁺ ions were observed in different SiN_x:Tb³⁺ films. And the PL intensity increased with annealing temperature. The defect states of N and Si dangling bonds of the SiN_x substrate had little effect on the light emission of Tb³⁺ after the high-temperature annealing. For the annealed Si-rich SiN_x (SRN) film, Si nanoclusters precipitated from the host matrix. The increased oxygen concentration and the optical absorption due to the band tail states and Si nanoclusters of the annealed SRN film decreased the light emission of Tb³⁺ ions