Abstract

Silicon multilayer thin films consisting of alternating amorphous SiOx (a-SiOx) and nanocrystalline silicon (nc-Si) layers were fabricated on p-type silicon substrates using a sol-gel spin-coating method. Boron-doped silicon powders, prepared through prolonged grinding, were mixed with a TEOS–ethanol sol-gel solution, and two nc-Si layers embedded in a-SiOx were sequentially deposited. The as-grown films were annealed at 100–400 °C and characterized using Raman spectroscopy, GXRD, FTIR, SEM, Resistivity and UV spectroscopy to analyze their structural, chemical, optical, and electronic properties. Annealing progressively enhanced crystallinity and increased the <111> and <110> grain sizes to ~11 nm and ~12 nm, respectively. Films annealed at higher temperatures showed a minimum mobility of ~37.5 cm²/V·s, maximum resistivity of ~7.35 Ω-cm, and a decreasing optical bandgap. Enhanced nanocrystal growth, reduced defects, and improved structural ordering intensified the 520 cm⁻¹ Raman peak. The multilayer architecture further strengthened these effects by offering additional nucleation sites, controlled nanocrystal confinement, defect-relaxing interfaces, improved phonon transport, and enhanced Si diffusion, resulting in superior crystalline quality.

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