Dae Won Moon

Sputter damage in Si surface by low energy Ar+ ion bombardment

Abstract The damage distributions in Si(1xa00xa00) surface after 1.0 and 0.5 keV Ar+ ion bombardment were studied using MEIS and Molecular dynamic (MD) simulation. The primary Ar+ ion beam direction was varied from surface normal to glancing angle. The MEIS results show that the damage thickness in 1.0 keV Ar ion bombardment is reduced from about 7.7 nm at surface normal incidence to 1.3 nm at the incident angle of 80°. However, the damage thickness in 0.5 keV Ar ion bombardment is reduced from 5.1 nm at surface normal incidence to 0.5 nm at the incident angle of 80°. The maximum atomic concentration of implanted Ar atoms after 1 keV ion bombardment is about 10.5 at% at the depth of 2.5 nm at surface normal incidence and about 2.0 at% at the depth of 1.2 nm at the incident angle of 80°. However, after 0.5 keV ion bombardments, it is 8.0 at% at the depth of 2.0 nm for surface normal incidence and the in-depth Ar distribution cannot be observable at the incident angle of 80°. MD simulation reproduced the damage distribution quantitatively.

Segregation of Si in Ge overlayers grown on Si(100) with hydrogen surfactant

Si surface segregation was studied quantitatively in Ge overlayers grown on Si(100)-(2×1) with medium energy ion scattering spectroscopy. The behavior of Si surface peak, as a function of Ge coverage, is explained with known growth structures in the Stranski–Krastanov Ge overlayers. We observed that the intermixing between Ge and Si is not significant in the presence of hydrogen surfactant. Possible microscopic models for the observed results are presented.

Atomic scale investigations of the Co/Pt(111) interface structure and magnetic properties

The interface structure of an ultrathin Co overlayer on a Pt(111) crystal was investigated with atomic-layer resolution medium-energy ion scattering spectroscopy and surface magneto-optical Kerr effect (SMOKE). For a 7 ML Co, interdiffusion begins at 673 K to form a heavily distorted Co–Pt surface alloy layer with little change in SMOKE intensity. However, annealing at 773 K formed a 30 atomic-layer-thick Co–Pt substitutional alloy with 3.7% maximum tensile strain, at which the SMOKE intensity increased more than 200%. The enhancement of the Kerr intensity is discussed with the interface alloy formation.

Intermixing in Stranski–Krastanov germanium overlayer on Si(100)

The growth behaviors of Stranski–Krastanov Ge overlayers on the Si(100)-(2×1) surface were studied with a combination of scanning tunneling microscopy and medium energy ion scattering spectroscopy. At the growth temperature of 350u200a°C, as Ge coverage increases, the Si surface peak in the channeling spectra decreases due to the shadowing of Ge atoms and can be fitted by a simple growth model at the Ge coverage less than 4 monolayers. At Ge coverages between 4 and 8 monolayers, the Si surface peak shows a broad enhancement, which can be explained with the growth of hut pits and that of three-dimensional hut clusters at the expense of Ge wetting layers.

Interface strain profiling in ultrathin SiO2 gate oxides with medium energy ion scattering spectroscopy

Abstract Medium energy ion scattering spectroscopy (MEIS) could identify ∼1 nm interface layer with compressive strain, which depends sensitively on the interface treatment conditions such as oxynitridation, ozone oxidation, tilt of Si(0xa00xa01) substrates. The interface strain relaxation always shows improvements in gate oxide reliability. Atomic scale investigations of strain profiles with MEIS are reviewed for SiO 2 /Si(0xa00xa01) interfaces.