Structural and phonon properties of InN synthesized by ion implantation in SiO₂

Ion-implantation is a powerful technique for the formation of compound semiconductor nanocrystal precipitates in a host medium. The aim is to elaborate quantum dots for device technology purposes. High dose (5.2 × 10¹⁶ ions/cm²) implantations of Indium (In) and Nitrogen (N) ions have been performed in a 206 nm thick SiO₂ layer thermally grown on < 111 > silicon. The implantation energies have been chosen from 12 to 180 keV to produce 5–10 at.% profiles overlapping at a mean depth of about 100 nm. Thermal treatments between 500 °C and 900 °C for different annealing times lead to the formation of InN nanometric precipitates and to cure the oxide defects. In addition, the In₂O₃ and metallic indium phases have been observed. Their sizes, crystalline structures and depth distributions have been studied as a function of annealing temperature using grazing incidence X-ray diffraction, transmission electron microscopy, Rutherford back scattering spectrometry and Raman spectroscopy. - Highlights: • InN nanocrystals were formed by sequential ion implantation of In and N in SiO₂. • The In₂O₃ and metallic indium phases have been found. • Redistribution of In occurs during post-implantation thermal annealing. • Three different InN family sizes were observed in the SiO₂ layer.