Dielectric Function of Native Oxide on Ion-Implanted GaAs

The main aim of the reported investigations is the influence of ion implantation on formation of native oxide layers and their optical spectra. Silicon implanted (100)-oriented GaAs crystalline wafers were used as substrates. The samples have been implanted with $Ne^{+}$, $Al^{+}$, $Ar^{+}$, or $In^{+}$ ions at energies of 100, 120, 150, and 250 keV, respectively. The implantations were carried out at a fluence of $1 \times 10^{16} cm^{-2}$ at 300 K. The refraction index spectral dependence for native oxide was approximated using the Cauchy equations. The dielectric function spectra of the native oxide layers on GaAs implanted with different ions have been obtained by variable angle spectroscopic ellipsometer in the 250-900 nm range using complementary information from the Rutherford backscattering/nuclear reactions measurements. The investigations showed that both real and imaginary parts of the dielectric function increase with mass of the ion species used for implantation.