Photoluminescence of ion-synthesized 9R-Si inclusions in SiO₂/Si structure: Effect of irradiation dose and oxide film thickness

The study of hexagonal silicon polytypes attracts special attention due to their unique physical properties compared to the traditional cubic phase of Si. Thus, for some hexagonal phases, a significant improvement in the emission properties has been demonstrated. In this work, the luminescent properties of SiO₂/Si structures irradiated with Kr⁺ ions at different doses and annealed at 800 °C have been systematically investigated. For such structures, a photoluminescence line at ∼ 1240 nm is observed and associated with the formation of hexagonal 9R-Si phase inclusions. It is found that the variation in the thickness of oxide film and the relative position of ion distribution profile and film/substrate interface leads to a regular change in the luminescence intensity. The nature of the observed dependencies is discussed as related mainly to the interplay between the factors contributing to the formation of 9R-Si inclusions and the generation of radiation defects in the Si substrate—centers of nonradiative recombination. The revealed regularities suggest optimal ion irradiation conditions for synthesis of optically active 9R-Si phase in diamond-like silicon.