| 1. |
- Wang, Xin, et al.
(författare)
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Growth of SrTiO3 thin films on LaAlO3(001) substrates, the influence of growth temperature on composition, orientation, and surface morphology
- 2000
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 360:1-2, s. 181-186
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Tidskriftsartikel (refereegranskat)abstract
- SrTiO3 films have been grown on LaAlO3(001) single crystal substrates using rf-sputtering. The substrates were held at temperatures ranging from 100 to 850°C. For growth temperatures as low as 350°C epitaxial growth is observed. Below 350°C the films are polycrystalline and three different orientations (100), (110), and (111) can be observed using X-ray diffraction. Atomic force microscopy shows that films deposited at temperatures below 350°C and above 650°C are smooth while the surfaces of the films made at intermediate temperatures are rough and faceted. As growth temperatures decrease below 250°C, the films show decreasing amount of Sr.
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| 2. |
- Agnarsson, Björn, et al.
(författare)
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Investigation on the role of indium in the removal of metallic gallium from soft and hard sputtered GaN (0001) surfaces
- 2009
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 517:21, s. 6023-6026
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Tidskriftsartikel (refereegranskat)abstract
- Cleaning of GaN by argon sputtering and subsequent annealing introduces metallic gallium on the GaN surface. Once formed, this metallic gallium can be difficult to remove. it has a strong influence on the Fermi level position in the band gap and poses a problem for subsequent epitaxial growth on the surface. We present a method of removing metallic gallium from moderately damaged GaN surfaces by deposition of indium, and formation of an In-Ga alloy that can be desorbed by annealing at similar to 550 degrees C. After the In-Ga alloy has desorbed, photoemission spectra show that the Ga3d bulk component becomes narrower indicating a smoother and more homogeneous surface. This is also reflected in a sharper low energy electron diffraction pattern. On heavily damaged GaN surfaces, caused by hard sputtering, larger amount of metallic gallium forms after annealing at 600 degrees C. This gallium readily alloys with deposited indium, but the alloy does not desorb until a temperature of 840 degrees C is reached and even then, traces of both indium and metallic gallium could be found on the surface.
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| 3. |
- Agnarsson, Björn, 1977, et al.
(författare)
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Rutile TiO 2 thin films grown by reactive high power impulse magnetron sputtering
- 2013
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 545, s. 445-450
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Tidskriftsartikel (refereegranskat)abstract
- Thin TiO 2 films were grown on Si(001) substrates by reactive dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS) at temperatures ranging from 300 to 700 C.Optical and structural properties of films were compared both before and after post-annealing using scanning electron microscopy, low angle X-ray reflection (XRR), grazing inc idence X-ray diffractometry and spectroscopic ellipsometry.Both dcMS- and HiPIMS-grown films reveal polycrystalline rutile TiO 2 , even prior to post-annealing.The HiPIMS-grown films exhibit significantly larger grains compared to that of dcMC-grown films, approaching 100% of the film thickness for films grown at 700 C.In addition, the XRR surface roughness of HiPIMS-grown films was significantly lower than that of dcMS-grown films over the whole temperature range 300-700 C.Dispersion curves could only be obtained for the HiPIMS-grown films, which were shown to have a refractive index in the range of 2.7-2.85 at 500 nm.The results show that thin, rutile TiO 2 films, with high refractive index, can be obtained by HiPIMS at relatively low growth temperatures, without post-annealing.Furthermore, these films are smoother and show better optical characteristics than their dcMS-grown counterparts.© 2013 Elsevier B.V.All rights reserved.
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| 4. |
- Agnarsson, Björn, et al.
(författare)
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The effect of hard nitridation on Al(2)O(3) using a radio frequency operated plasma cell
- 2011
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 519:22, s. 7796-7802
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Tidskriftsartikel (refereegranskat)abstract
- We report on an atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) investigation of hard nitridation of sapphire (alpha.-Al(2)O(3)) substrate, using an Epi UNI-Bulb RF plasma cell at substrate temperatures ranging from 250 to 600 degrees C. Our results show that an AlN(1-x)O(x) layer forms on sapphire after extended nitridation at all temperatures, following a Stranski-Krastanov growth mode, with less islands forming at higher temperatures. We also observe a layer-dependent charging shift in XPS, separating smooth AlN(1-x)O(x) layers from rough AlN(1-x)O(x) islands due to their different electronic coupling to the substrate. Although the island growth is suppressed at higher temperatures, the surface roughness increases at higher temperatures as seen by AFM. We also observe sputtering effects with protrusions and pits.
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| 5. |
- Gylfason, Kristinn B., 1978-, et al.
(författare)
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In-situ resistivity measurements during growth of ultra-thin Cr_0.7Mo_0.3
- 2006
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 515:2, s. 583-586
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Tidskriftsartikel (refereegranskat)abstract
- The growth of ultra-thin, lattice matched, Cr0.7Mo0.3 films on an MgO substrate, in a dc magnetron discharge, was investigated by in situ measurements in order to determine the minimum thickness of a continuous layer. The thickness dependence of the resistivity shows a coalescence thickness of less than two monolayers indicating layer by layer growth of the films. We compare the resistivity of the films to a combination of the Fuchs- Sondheimer and the Mayadas-Shatzkes models, assuming a thickness dependence of grain size. The model indicates that grain size increases with increasing growth temperature.
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| 6. |
- Ingason, A. S., et al.
(författare)
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Growth and structural properties of Mg:C thin films prepared by magnetron sputtering
- 2010
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 518:15, s. 4225-4230
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the growth and structure properties of Mg:C thin films. The films are prepared using a dc magnetron sputtering discharge where the electrical resistance over the films is monitored during growth in-situ with a four point probe setup. The structural properties of the films are investigated using X-ray diffraction measurements and the elemental composition and binding in the films is determined using elastic recoil detection analysis and X-ray photoelectron spectroscopy. The results show that during co-sputtering the carbon flux influences the initial stages of the film growth. The films are made of polycrystalline magnesium grains embedded in a carbon network, the size of which depends on the carbon content, but amorphous phases cannot be excluded. The XPS measurements show the presence of carbidic carbon whereas X-ray measurements find no Mg:C phases. The overall stability of the films is found to depend on the carbon content, where stable films capped with a 14 nm Pd layer cannot be obtained with carbon content above 18%.
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| 7. |
- Magnus, F, et al.
(författare)
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Morphology of TiN thin films grown on SiO(2) by reactive high power impulse magnetron sputtering
- 2011
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 520:5, s. 1621-1624
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Tidskriftsartikel (refereegranskat)abstract
- Thin TiN films were grown on SiO(2) by reactive high power impulse magnetron sputtering (HiPIMS) at a range of temperatures from 45 to 600 degrees C. The film properties were compared to films grown by conventional dc magnetron sputtering (dcMS) at similar conditions. Structural characterization was carried out using X-ray diffraction and reflection methods. The HiPIMS process produces denser films at lower growth temperature than does dcMS. Furthermore, the surface is much smoother for films grown by the HiPIMS process. The [200] grain size increases monotonically with increased growth temperature, whereas the size of the [111] oriented grains decreases to a minimum for a growth temperature of 400 degrees C after which it starts to increase with growth temperature. The [200] crystallites are smaller than the [111] crystallites for all growth temperatures. The grain sizes of both orientations are smaller in HiPIMS grown films than in dcMS grown films.
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| 8. |
- Qi, B., et al.
(författare)
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High-resolution X-ray photoemission spectroscopy study of AlN nano-columns grown by nitridation of Al nano-squares on Si(111) substrates with ammonia
- 2010
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 518:14, s. 3632-3639
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Tidskriftsartikel (refereegranskat)abstract
- The growth of AlN nano-columns by ammonium nitridation of Al nano-squares embedded in SiO2 on Si(111) substrates was studied by high-resolution X-ray photoemission spectroscopy from a synchrotron radiation source and scanning electron microscopy (SEM). Selective nitridation of the Al nano-squares on the SiO2 mask was obtained in the temperature window of 600 degrees C-700 degrees C. The well-shaped AlN nano-column arrays with diameters confined by the lateral size of the Al nano-squares (similar to 100 nm) were observed in SEM.
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| 9. |
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| 10. |
- Qi, B., et al.
(författare)
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Photoemission and low energy electron microscopy study on the formation and nitridation of indium droplets on Si (111)7 x 7 surfaces
- 2013
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 531, s. 61-69
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Tidskriftsartikel (refereegranskat)abstract
- The formation and nitridation of indium(In) droplets on Si (1 1 1)7 x 7, with regard to In droplet epitaxy growth of InN nanostructures, were studied using a spectroscopic photoemission and low energy electron microscopy, for the In coverages from 0.07 to 2.3 monolayer (ML). The results reveal that the In adatoms formed well-ordered clusters while keeping the Si (1 1 1)7 x 7 surface periodicity at 0.07 ML and a single root 3 x root 3 phase at 0.3 ML around 440-470 degrees C. At 0.82 ML, owing to the presence of structurally defect areas beside the 7 x 7 domains, 3-D In droplets evolved concomitantly with the formation of 4 x 1-In cluster chains, accompanied by a transition in surface electric property from semiconducting to metallic. Further increasing the In to 2.3 ML led to a moderate increase in number density and an appreciable lateral growth of the droplets, as well as the multi-domain In phases. Upon nitridation with NH3 at similar to 480 degrees C, besides the nitridation of the In droplets, the N radicals also dissociated the In - Si bonds to form Si - N. This caused a partial disintegration of the ordered In phase and removal of the In adatoms between the In droplets.
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