Charge-state dependence of energy loss of MeV dimers inGaAs(100)

Abstract

Carbon and oxygen dimers with charge states $1+$ and $3+$ were implanted into $\mathrm{GaAs}$ along the [100] direction at an energy of $0.5\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}∕\mathrm{atom}$. The defect depth profiles are extracted from Rutherford backscattering spectrometry and channeling. The depth profile of carbon is extracted from secondary ion mass spectrometry measurements. The defect density produced by dimer ions is larger than monomer ions. The depth profile of carbon in dimer implanted $\mathrm{GaAs}$ is deeper than that of monomer implanted $\mathrm{GaAs}$ showing negative molecular effect. The defect depth profile of oxygen dimer implanted $\mathrm{GaAs}$ is deeper for $3+$ than that for $1+$ charge state. This indicates that energy loss of ${\mathrm{O}}_{2}^{3+}$ is smaller than that of ${\mathrm{O}}_{2}^{+}$. It is attributed to charge asymmetry and a higher degree of alignment of ${\mathrm{O}}_{2}^{3+}$ along the [100] axis of $\mathrm{GaAs}$.