Phase Transformations and Structural Transformations of Manganese Silicides in the Si-Mn System
Аннотация
A comprehensive investigation of thermally induced phase transformations in the silicon-manganese (Si–Mn) system was conducted. The study utilized X-ray diffraction (XRD), Raman spectroscopy (including chemical Raman mapping), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDS), deep-level transient spectroscopy (DLTS), and thermodynamic CALPHAD modeling. The sequence of transformations has been reliably reconstructed as follows: (i) interstitial incorporation of Mn and partial amorphization of the near-surface Si layer; (ii) nucleation and growth of MnSi (B20 structure, P2₁3); (iii) stabilization of the higher silicide phase Mn₄Si₇ under Si-rich conditions; (iv) at T ≫ 900 °C, a partial reverse transformation to MnSi. DLTS analysis revealed three electrically active deep-level centers with activation energies of Eс–0.53 eV, Eс–0.43 eV, and Eс–0.20 eV (σn ≈ 10⁻¹⁶–10⁻¹⁵ cm²), which correlate with the MnSi → Mn₄Si₇ transition and interface traps at the “silicide/Si” boundary. CALPHAD modeling confirmed negative Gibbs free energies of formation (ΔGf) and identified thermodynamic stability windows for MnSi (600–750 °C) and Mn₄Si₇ (800–950 °C). The resulting process map provides the technological parameters for synthesizing CMOS-compatible Si–Mn structures.