Raman study of silicon telluride nanoplates and their degradation

Silicon telluride (Si₂Te₃) has emerged as one of the many contenders for 2D materials ideal for the fabrication of atomically thin devices. Despite the progress which has been made in the electric and optical properties of silicon telluride, much work is still needed to better understand this material. We report here on the Raman study of Si₂Te₃degradation under both annealing andin situheating with a laser. Both processes caused pristine Si₂Te₃to degrade into tellurium and silicon oxide in air in the absence of a protective coating. A previously unreported Raman peak at ∼140 cm^-1was observed from the degraded samples and is found to be associated with pure tellurium. This peak was previously unresolved with the peak at 144 cm^-1for pristine Si₂Te₃in the literature and has been erroneously assigned as a signature Raman peak of pure Si₂Te₃, which has caused incorrect interpretations of experimental data. Our study has led to a fundamental understanding of the Raman peaks in Si₂Te₃, and helps resolve the inconsistent issues in the literature. This study is not only important for fundamental understanding but also vital for material characterization and applications.