Ion-implantation induced anomalous surface amorphization in silicon

Spectroscopic ellipsometry (SE), high-depth-resolution Rutherford backscattering (RBS) and channeling have been used to examine the surface damage formed by room temperature N and B implantation into silicon. For the analysis of the SE data we used the conventional method of assuming appropriate optical models and fitting the model parameters (layer thicknesses and volume fraction of the amorphous silicon component in the layers) by linear regression. The dependence of the thickness of the surface-damaged silicon layer (beneath the native oxide layer) on the implantation parameters was determined: the higher the dose, the thicker the disordered layer at the surface. The mechanism of the surface amorphization process is explained in relation to the ion beam induced layer-by-layer amorphization. The results demonstrate the applicability of Spectroscopic ellipsometry with a proper optical model. RBS, as an independent cross-checking method supported the constructed optical model

Kraftutbygging i Bøelva, Telemark. Konsekvenser for resipientforhold og fiske

På grunnlag av tidligere undersøkelsesresultater, innsamlete opplysninger og utførte beregninger er det foretatt en vurdering av konsekvenser overfor resipientforhold og fiske av planlagt kraftutbygging i Bøelva i Telemark. Det antas at utbyggingen bl.a. vil kunne føre til nedsatt resipientkapasitet, økt begroing av alger og høyere vegetasjon, og skadevirkninger overfor fisket på enkelte strekninger. Det er gitt forslag til praktiske tiltak som kan redusere skadevirkningeneUtvalget for utbygging av Bøfossan

Kraftutbygging i Bøelva, Telemark. Konsekvenser for resipientforhold og fiske

På grunnlag av tidligere undersøkelsesresultater, innsamlete opplysninger og utførte beregninger er det foretatt en vurdering av konsekvenser overfor resipientforhold og fiske av planlagt kraftutbygging i Bøelva i Telemark. Det antas at utbyggingen bl.a. vil kunne føre til nedsatt resipientkapasitet, økt begroing av alger og høyere vegetasjon, og skadevirkninger overfor fisket på enkelte strekninger. Det er gitt forslag til praktiske tiltak som kan redusere skadevirkningen

Nanoscale morphology and photoemission of arsenic implanted germanium films

Germanium films of 140 nm thickness deposited onto Si substrate were implanted with 70 keV arsenic ions with a dose of 2.5x10(14) cm(-2). The morphology of the implanted films was determined by Rutherford backscattering and cross-sectional transmission electron microscopy. Concentration of oxygen and carbon impurities and their distribution in the implanted layer were detected by secondary-ion-mass spectroscopy and nuclear reaction analysis using the O-16(He-4,He-4)O-16 reaction. The depth dependence of the valence band density of states was investigated by measuring the energy distribution curve of photoelectrons using Ar ion etching for profiling. The morphology of As implanted film was dominated by nanosized (10-100 nm) Ge islands separated by empty bubbles at a depth of 20-50 nm under the surface. At depth ranges of 0-20 and 70 to a measured depth of 140 nm, however, morphology of the as-evaporated Ge film was not modified. At a depth of 20-50 nm, photoelectron spectra were similar to those obtained for Ge amorphized with heavy ion (Sb) implantation [implantation induced (I.I.) a-Ge]. The depth profile of the morphology and the photoemission data indicate correlation between the morphology and valence band density of states of the ion I.I. a-Ge. As this regime was formed deep in the evaporated film, i.e., isolated from the environment, any contamination, etc., effect can be excluded. The depth distribution of this I.I. a-Ge layer shows that the atomic displacement process cannot account for its formation

Formation of iron silicide layers on Si by ion implantation and laser beams / R.M. Bayazitov, R.l. Batalov, G.D Ivlev, E.l.Gatskevich, I. Dezsi, E. Kotai

Исследованы процессы синтеза тонких пленок силицидов железа (FeSi и β-FeSi2) на подложке Si (100), имплантированной Fe+ (D=1016 - 2 X 1017 см-2) при импульсной лазерной обработке (λ = 0.69 мкм, т = 80 нс) в диапазоне плотностей энергии W = 0.6 - 1,4 Дж/см2. Методами рентгеновской дифракции, просвечивающей электронной микроскопии и резерфордовского обратного рассеяния изучены структура и фазовый состав синтезированных пленок, а также поведение примеси Fe в Si. Показано, что лазерный отжиг (W= 0,6 - 1.1 Дж/см2, D = 1.8 х 1017 см-2) приводит к формированию эпитаксиальных слоев стехиометрического моносилицида железа FeSi. Повышение энергии в импульсе до 1.4 Дж/см2 сопровождается образованием характерной для жидкофазной кристаллизации ячеистой структуры, состоящей из колонн монокристаплического Si с поперечными размерами 30 - 40 нм, разделенных границами из смеси силицидных фаз (FeSi+ β-FeSi2). В случае малых доз имплантации (D ~ 1016 см-2) ячеистая структура формируется при меньших энергиях в импульсе (~ 0.8 Дж/см2). При этом наблюдается характерное для малорастворимых в Si примесей вытеснение внедренного Fe к поверхности