学术文献库

Although silicon oxynitrides are important semiconductors for many practical applications, their potential second-order nonlinear optical (NLO) applications, regardless of balanced or controllable performance, have never been systemically explored. Using the first-principles calculations, in this article, we discover that the sinoite (i.e., typical silicon oxynitride Si2N2O) can simultaneously exhibit wide optical bandgap, strong second-harmonic generation (SHG) effect, and large birefringence, which are further confirmed by our preliminary experimental data. Importantly, we propose that alloying engineering can be further applied to control the balanced NLO properties in the Si2N2O system. Combining first-principles calculations and cluster expansion theory, we demonstrate that alloying Ge into Si2N2O can easily form low formation energy Si2(1-x)Ge2xN2O alloys, which can in turn achieve controllable phase-matching harmonic output with high SHG efficiency at different energy ranges. Therefore, alloy engineering could provide a unique approach to effectively control the balanced NLO performance of Si2(1-x)Ge2xN2O, making this polar alloy system holding potential applications in tunable laser frequency conversion and controllable all-optical devices.