Topographic and crystallographic characterization of a grazing-ion-bombarded GaAs(110) surface by time-of-flight ion-scattering spectrometry

J.E. GAYONE; R.G. PREGLIASCO; G.R. GOMEZ; E.A. SANCHEZ; O. GRIZZI

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

AMER PHYSICAL SOC

Lugar: ..; Año: 1997 vol. 56 p. 4186 - 4193

0163-1829

We studied the topography and the atomic structure of a clean GaAs(110) surface By time-of-flight ionscattering spectrometry (TOF-ISS). In a first series of measurements the surface was cleaned by standard cycles of ion bombardment and annealing ~500 eV Ar+, 500 °C!. This method was very efficient to remove surface contaminants but not to smooth out the damage produced in TOF-ISS experiments. A cleaning method consisting of grazing bombardment with 20 keV Ar+ combined with annealing at 500 °C resulted in a clear improvement of the surface flatness. This was confirmed by measurements of electron energy distributions recorded under grazing proton bombardment and by a topographical analysis with an atomic force microscope. The crystallographic structure of the grazing ion bombarded surface was then studied by TOF-ISS. The quasisingle backscattered intensity measured for 5 keV Ne1 presented strong variations with the incident and azimuthal angles which are consistent with the generally accepted relaxed GaAs~110! surface. From the comparison of critical angles measured and focusing regions calculated with a code recently developed we have obtained an As-Ga first interlayer spacing DZ5(0.6660.08)Å, and the spacings between the first and second As layers DZ1,2(As)=(2.25+-0.08) Å and between the first and second Ga layers DZ1,2(Ga)=(1.57+-0.1) Å