Stoichiometry changes in III–V compounds under ion bombardment

Abstract GaAs and GaP single crystalline samples were implanted/sputtered with N, O, Ar and Te ions to doses >10 17 cm −2 at energies corresponding to several hundred angstroms of projected range. Depth distributions of the implanted atoms along with those of both constituents of the substrate were measured by the combined low-and-high-energy backscattering techniques. Residual damage within and beneath the irradiated region was examined by the use of photoluminescence spectroscopy. For GaAs a strong depletion of the group V component observed in the surface region after high-dose oxygen implantation and relatively small changes in stoichiometry under argon or tellurium bombardment suggest a mechanism in which a cascade-driven chemical interaction between the colliding atoms is responsible for preferential sputtering. In addition, analysis of the luminescence spectra indicates that the distribution of corresponding vacancies extends to depths well below the range of implanted ions. For GaP, no evidence of substantial stoichiometry modifications was found; this behaviour, very different to that of GaAs, may be attributed to the absence of highly volatile GaP-based oxygenated species.