• Journal of Surface Science and Engineering
• /
• v.29 no.5
• /
• pp.399-406
• /
• 1996

The orientational cross-over phenomena in an RF sputtering growth of TiN films were studied in an in-situ, real-time synchrotron x-ray scattering experiment. For the films grown with pure Ar sputtering gas, the cross-over from the more strained (002)-oriented grains to the less strained (111)-oriented grains occurred as the film thickness was increased. As the sputtering power was increased, the cross-over thickness, at which the growth orientation changes from the <002> to the <111> direction, was decreased. The addition of $N_2$ besides Ar as sputtering gas suppressed the cross-over, and consequently resulted in the (002) preferred orientation without exhibiting the cross-over. We attribute the observed cross-over phenomena to the competition between the surface and the strain energy. The x-ray powder diffraction, the x-ray reflectivity, and the ex-situ AFM surface topology study consistently suggest that the microscopic growth front was in fact always the (002) planes. In the initial stage of growth, the (002) planes were aligned to the substrate surface to minimize the surface energy. At later stages, however, the (002) growth front tilted away from the surface by about $60^{\circ}$ to relax the strain, which caused the cross-over of the preferred growth direction to the <111> direction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.05b
• /
• pp.79-83
• /
• 2001

In order to compare the barrier properties of Ta-N/Si(001) with those of Ta-N/Ta/Si(001), we studied structural properties of films grown by RF magnetron sputtering with various $Ar/N_2$ ratios. To evaluate the barrier properties, the samples were annealed in a vacuum chamber. Ex-situ x-ray scattering measurements were done using an in-house x-ray system. With increasing nitrogen ratio in Ta-N/Si(001), the barrier property of Ta-N/Si(001) was enhanced, finally failed at $750^{\circ}C$ due to the crystallization and silicide formation. Compared with Ta-N/Si(001), Ta-N/Ta/Si(001) forms silicides at $650^{\circ}C$. However it does not crystallize even at $750^{\circ}C$. With increasing nitrogen composition in Ta-N/Ta/Si(001), the formation of tantalum silicide was reduced and the surface roughness was improved. To observe the surface morphology of Ta-N/Ta/Si(001) during annealing, we performed an in-situ x-ray scattering experiment using synchrotron radiation of the 5C2 at Pohang Light Source(PLS). Addition of Ta layer between Ta-N and Si(001) improved the surface morphology and reduced the surface degradation at high temperatures. In addition, increasing $N_2/Ar$ flow ratio reduced the formation of tantalum silicide and enhanced the barrier properties.

• Journal of the Korean Vacuum Society
• /
• v.2 no.2
• /
• pp.171-180
• /
• 1993

X-ray photoelectron diffraction (XPD) is used to characterize the crystallographically cleaved GaAs(110) surface. By using polar and azimuthal scans of the usual angle-resolved x-ray photoelectron spectroscopy, we get the reconstruction geometry of the clean GaAs(110) surface from the intensity ratio of Ga 3d core-level peaks. The reconstruction parameters are determined by fitting the diffraction pattern with the single scattering cluster (SSC) model, and the results show similar tendencies to those obtained by other techniques.

• Macromolecular Research
• /
• v.10 no.1
• /
• pp.2-12
• /
• 2002

The small-angle X-ray scattering (SAXS) beamline BL4C1 at the 2.5 GeV storage ring of the Pohang Accelerator Laboratory (PAL) has been in its first you of operation since August 2000. During this first stage it could meet the basic requirements of the rapidly growing domestic SAXS user community, which has been carrying out measurements mainly on various polymer systems. The X-ray source is a bending magnet which produces white radiation with a critical energy of 5.5 keV. A synthetic double multilayer monochromator selects quasi-monochromatic radiation with a bandwidth of ca. 1.5%. This relatively low degree of monochromatization is sufficient for most SAXS measurements and allows a considerably higher flux at the sample as compared to monochromators using single crystals. Higher harmonics from the monochromator are rejected by reflection from a flat mirror, and a slit system is installed for collimation. A charge-coupled device (CCD) system, two one-dimensional photodiode arrays (PDA) and imaging plates (IP) are available its detectors. The overall performance of the beamline optics and of the detector systems has been checked using various standard samples. While the CCD and PDA detectors are well-suited for diffraction measurements, they give unsatisfactory data from weakly scattering samples, due to their high intrinsic noise. By using the IP system smooth scattering curves could be obtained in a wide dynamic range. In the second stage, stating from August 2001, the beamline will be upgraded with additional slits, focusing optics and gas-filled proportional detectors.

• Polymer Science and Technology
• /
• v.8 no.4
• /
• pp.467-473
• /
• 1997

• Proceedings of the Korean Magnestics Society Conference
• /
• 1998.10a
• /
• pp.74-75
• /
• 1998

• Polymer Science and Technology
• /
• v.8 no.3
• /
• pp.353-359
• /
• 1997

• Journal of Radiation Protection and Research
• /
• v.34 no.1
• /
• pp.25-30
• /
• 2009

Micro-columnar CsI(Tl) is the most popular scintillator material which is used for many indirect digital X-ray imaging detectors. The light scattering at the surface of micro-columnar CsI(Tl) scintillator was studied to find the correlation between the surface roughness and the resultant image resolution of indirect X-ray imaging detectors. Using a commercially available optical simulation program, Light Tools, MTF (Modulation Transfer Function) curves of the CsI(Tl) film thermally evaporated on glass substrate with different thickness were calculated and compared with the experimental estimation of MTF values by the edge X-ray image method and CCD camera. It was found that the standard deviation value of Gaussian scattering model which is determined by the surface roughness of micro-columns could certainly change the MTF value of image sensors. This model and calculation methodology will be beneficial to estimate the overall performance of indirect X-ray imaging system with CsI(Tl) scintillator film for optimum design depending on its application.

• Applied Microscopy
• /
• v.33 no.4
• /
• pp.251-259
• /
• 2003

In this review, the sources and the characteristics of X-rays and electrons and their interactions with matters were described in terms of the atomic scattering factors. The geometrical diffraction conditions were taken into account in terms of Ewald spheres in reciprocal lattice spaces. The effects of the finite size of sources and detectors on diffractions were also considered.

• Journal of the Korean Vacuum Society
• /
• v.14 no.3
• /
• pp.147-152
• /
• 2005

The structural evolution of $Ni(400\;\AA)/Au(400\;\AA)$ films on p-type GaN during thermal oxidation in ai. was investigated by in situ x-ray scattering experiments. These results indicate that Ni layer and Au layer intermix during thermal oxidation. Au-rich solid solutions containing the different amount of Ni atoms are formed during oxidation. The Ni atoms in Au-rich solid solution out-diffuse as the oxidation proceeds resulting in the formation of NiO(111) phase. Despite of the complete oxidation at $650^{\circ}C$, the position of bulk Au(111) diffraction profile indicates that small amount of Wi atoms are still incorporated in the Au phase.