Study of silicon doped with zinc ions and annealed in oxygen

The results of studies of the surface layer of silicon and the formation of precipitates in Czochralski n-Si (100) samples implanted with ⁶⁴Zn⁺ ions with an energy of 50 keV and a dose of 5 × 10¹⁶ cm^–2 at room temperature and then oxidized at temperatures from 400 to 900°C are reported. The surface is visualized using an electron microscope, while visualization of the surface layer is conducted via profiling in depth by elemental mapping using Auger electron spectroscopy. The distribution of impurity ions in silicon is analyzed using a time-of-flight secondary-ion mass spectrometer. Using X-ray photoelectron spectroscopy, the chemical state of atoms of the silicon matrix and zinc and oxygen impurity atoms is studied, and the phase composition of the implanted and annealed samples is refined. After the implantation of zinc, two maxima of the zinc concentration, one at the wafer surface and the other at a depth of 70 nm, are observed. In this case, nanoparticles of the Zn metal phase and ZnO phase, about 10 nm in dimensions, are formed at the surface and in the surface layer. After annealing in oxygen, the ZnO · Zn₂SiO₄ and Zn · ZnO phases are detected near the surface and at a depth of 50 nm, respectively.