| 1. |
- Kakanakova-Georgieva, Anelia, 1970-, et al.
(författare)
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Interface chemistry of a Ti/ Au/ Pt/ Ti/ SiC structure
- 1997
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 121/122, s. 208-212
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Tidskriftsartikel (refereegranskat)abstract
- X-ray photoelectron spectroscopy (XPS) is used to investigate the chemical reactions and diffusion processes at Ti/Au/Pt/Ti/SiC interfaces for as deposited and annealed at 575°C for 10 min structures. The distribution of the elements and the change in their chemical state has been studied. The XP spectra indicate titanium carbide and platinum silicides formation at the SiC interface, which is preceded by the dissociation of SiC due to the reactivity of Ti at 575°C. TiC represents a barrier to the further diffusion of Ti to the SiC bulk and the Ti layer makes the diffusion of Pt into SiC difficult. The element distribution of the annealed structure demonstrates that Pt has diffused through almost the whole gold layer to the surface, an alloy of the two metals being formed.
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| 2. |
- Kakanakova-Georgieva, Anelia, 1970-, et al.
(författare)
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Interface chemistry of WN/4H-SiC structures
- 1999
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 151:3-4, s. 225-232
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Tidskriftsartikel (refereegranskat)abstract
- The interface chemistry of WN/4H–SiC structures has been studied by means of X-ray photoelectron spectroscopy (XPS). XPS investigations have been performed on as deposited, 800°C and 1200°C annealed (4 min) samples. The as deposited and 800°C annealed samples are characterized by chemically inert interfaces. Complete nitrogen out-diffusion from the WN layer, significant carbon diffusion into the contact layer, tungsten carbide and tungsten silicide formation occur during the 1200°C annealing process. The 800°C annealed WN/4H–SiC contacts are found to be of a Schottky type with a barrier height of 0.91 eV. The Schottky barrier height and the ideality factor show no significant changes during 100 h storage at 500°C under nitrogen and during operation at increasing temperature up to 350°C in air.
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| 3. |
- Marinova, Ts., et al.
(författare)
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XPS depth profiling of laser-annealed Zn+-implanted GaAs
- 1997
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 109/110, s. 80-86
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Tidskriftsartikel (refereegranskat)abstract
- Data on the effects of 140 keV Zn+-implantation in (100) GaAs and the consequent low power pulsed laser annealing (LPPLA) on the As/Ga ratio and the chemical states of the elements at the surface and in the subsurface region are presented. The results include the depth distribution of the elements for virgin, as-implanted and implanted+LPPLA [30×(4.5/7.5) MW/cm2] samples. The X-ray photoelectron spectra of as-implanted samples show that a low-intensity Zn 2p peak is observed after 20 min of Ar+ sputtering with an energy of 3 keV, corresponding to about 20 nm of etched material. The depth profiling XPS analysis confirms the ‘recovering' of the stoichiometry of Zn+-implanted specimens after LPPLA with laser pulses of a power density in the energy window of (5–7 MW/cm2). At laser pulse power densities outside of this energy window (4.5 and 7.5 MW/cm2) Zn appears again in the XP spectra after 20 min sputtering as in the case of as-implanted GaAs.
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