Yeongseok Zoo

Comparison of preferred orientation and stress in silver thin films on different substrates using x-ray diffraction

Silver thin films were deposited on SiO2 and polyethylene naphthalate (PEN) using e-beam evaporation. X-ray diffraction techniques were used to investigate the influence of substrate morphology on the Ag film’s texture. Different modes of texture were observed in Ag thin films on SiO2 and PEN. Detailed information regarding spatial distribution of specific {hkl} planes was obtained by conducting pole figure analyses. A typical stress measurement technique for thin films, sin2ψ analysis, was performed to study how the surface morphology of the various substrates affected the stress induced during the texture evolution of the thin films. Based on the data from this study, the preferred orientation and stress of Ag thin films on SiO2 and PEN were discussed.

Influence of defects and processing parameters on the properties of indium tin oxide films on polyethylene napthalate substrate

Indium tin oxide (ITO) thin films were deposited on polyethylene napthalate (PEN) by rf sputtering using different rf powers (60 and 120W) and at different substrate temperatures (room temperature and 100°C). Selected PEN substrates were pretreated using an Ar plasma before ITO sputter deposition. Rutherford backscattering spectrometry was used to determine the oxygen content in the films. Hall effect measurements were used to evaluate the electrical properties. In this paper the influence of defect structure, sputtering conditions, and the effect of annealing on the electrical and optical properties of ITO on PEN have been investigated. Electrical properties such as carrier concentration, mobility, and resistivity of the ITO films varied with rf power and substrate temperature. The electrical and optical properties of the films changed after annealing in air. This study also describes how the as-deposited amorphous ITO changes from amorphous to crystalline as a result of heat treatment, and investigates ...

Improved surface morphology and texture of Ag films on indium tin oxide via Cu additions

The surface and texture properties of Ag(Cu) alloy thin films on indium tin oxide (ITO) has been investigated and compared to pure Ag thin films on ITO. Atomic force microscopy (AFM) and x-ray diffraction results of annealed films show differences in the evolution of surface morphology and texture with annealing. The presence of Cu atoms in the silver alters the alloy’s surface energy and surface diffusion. This results in Ag and Ag(Cu) alloy having the very different surface morphology and crystallographic texture. The (111) texture of the Ag(Cu) is enhanced when compared to that of pure Ag films. The resistivity of Ag(Cu) films annealed at high temperatures (∼up to 600°C for 1h in vacuum) remained constant due to absence of agglomeration.

Copper enhanced (111) texture in silver thin films on amorphous SiO2

Small amounts (5at.%) of copper were added to silver thin films to improve adhesion and minimize agglomeration on SiO2 layers. Resistivity measurements from the Ag(Cu) films showed that small Cu additions do not significantly increase the resistivity compared to pure Ag. Texture evolution and surface morphology of Ag and Ag(Cu) thin films on SiO2 were also investigated using x-ray diffraction (XRD) techniques and atomic force microscopy. Normalized (111) θ-2θ XRD intensities increased from 91.6% to 96.8% upon addition of Cu, likely due to enhanced adatom diffusion resulting from the Cu addition. XRD pole figure analysis revealed differences in texture evolution between the Ag and Ag(Cu) thin films. Since high adatom surface diffusion of Cu promotes preferred grain growth of the Ag matrix, Ag(Cu) thin films showed enhanced (111) texture compared to Ag thin films. Glancing angle XRD results confirmed the evolution of (111) texture in the Ag and Ag(Cu) thin films. In the case of Ag, (111) texture was enhance...

Strain characterization of strained silicon on insulator including the effects of rotational misalignment

High resolution x-ray diffraction (XRD) techniques were used to characterize the perpendicular and parallel strains in strained Si-on-insulator (SSOI) layers. XRD profiles generated from the crystalline SSOI layer provided a direct measurement of the layer’s strain components. Calculated strain values, such as the compressive perpendicular and tensile parallel strains, were consistent with expected values. In addition, we have demonstrated that the rotational misalignment (Δϕ) between the layer and the substrate can be incorporated within the biaxial strain equations for epitaxial layers. Strain components calculated using the modified equations showed 1%–5% increase with respect to values obtained using typical strain relations. We observed an interesting phenomenon in that the tensile parallel strains increased from 0.56% to 0.7% upon annealing. This behavior was contrary to unconstrained strain relaxation but was consistent with layer constraint and the existence of finite stresses at the Si∕SiO2 inter...

Texture evolution and stress in silver thin films on different substrates using X-ray diffraction

Substrate surface roughness effects on Ag film texture were investigated using pole figure analysis. X-ray diffraction results confirmed that Ag thin films on smooth SiO2 substrates had strong {111} texture when compared with Ag films on PEN. It was noted that the difference of strain energy density (δ E e ) in Ag film on PEN (0.039 MPa) was almost 5 times greater than that on SiO 2 (0.0084 MPa). The comparison between surface and strain energies revealed that the {111} texture of Ag thin film on SiO 2 was explained by minimization of the surface energy and the weaker {111} texture of Ag on PEN was a result of reduced diffusion length of Ag adatoms on the rough PEN surface.