Analyzing atomic force microscopy images using spectral methods

Fang, Sychyi; Haplepete, S.; Chen, W.; Helms, C. R.; Edwards, Hal

doi:10.1063/1.366489

Cited by 140 publications

(90 citation statements)

References 26 publications

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“…We found the RMS roughness increases from 45 Å to 230 Å as we go to higher scan area. The RMS roughness is strongly dependent on the scan size [42,43]. This confirms that the sample surface has fractal geometry over several length scales [44].…”

Section: (D) a Comparison Of Dnr And Afm Measurementssupporting

confidence: 60%

Structure and morphology of Cu/Ni film grown by electrodeposition method: A study of neutron reflectivity and AFM

Singh

Basu

Ghosh

2009

Applied Surface Science

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We present a detailed study of the interface morphology of an electro-deposited (ED) Ni/Cu bilayer film by using off-specular (diffuse) neutron reflectivity technique and Atomic Force Microscopy (AFM). The Ni/Cu bilayer has been electro-deposited on seed layers of Ti/Cu. These two seed layers were deposited by magnetron sputtering. The depth profile of density in the sample has been obtained from specular neutron reflectivity data. AFM image of the air-film interface shows that the surface is covered by globular islands of different sizes. The AFM height distribution of the surface clearly shows two peaks [ Fig. 3] and the relief structure (islands) on the surface in the film can be treated as a quasi-two-level random rough surface structure. We have demonstrated that the detailed morphology of air-film interfaces, the quasi-two level surface structure as well as morphology of the buried interfaces can be obtained from off-specular neutron reflectivity data. We have shown from AFM and off-specular neutron reflectivity data that the morphologies of electro-deposited surface is distinctly different from that of sputter-deposited interface in this sample. To the best of our knowledge this is the first attempt to microscopically quantify the differences in morphologies of metallic interfaces deposited by two different techniques viz. electro-deposition and sputtering.

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Section: (D) a Comparison Of Dnr And Afm Measurementssupporting

confidence: 60%

Structure and morphology of Cu/Ni film grown by electrodeposition method: A study of neutron reflectivity and AFM

Singh

Basu

Ghosh

2009

Applied Surface Science

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“…PSD has been widely used on digital atomic force microscopy (AFM) images to achieve surface roughness information. [5][6][7] In this report, we introduce spatial Fourier transform and PSD as a method for quantitative analysis of TEM images of the polymer of the BHJ materials used in the fabrication of "plastic" solar cells.Polymer solar-cell devices were fabricated under optimum conditions which have been reported previously.[3] In order to relate device performance to morphology change we made TEM specimens using the same polymer film applied to device fabrication. As shown in Figure 1A and B, TEM images of the films were captured before and after annealing at 150°C for 10 min.…”

mentioning

confidence: 99%

Spatial Fourier‐Transform Analysis of the Morphology of Bulk Heterojunction Materials Used in “Plastic” Solar Cells

2007

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Polymer solar cells based on poly(3-hexylthiophene) (P3HT):fullerene bulk heterojunction (BHJ) materials have demonstrated promising (and continuously improving) performance and remarkable thermal stability. Extensive studies of the morphology have revealed that polymer solar cell performance depends strongly on the nanoscale phase separation of the P3HT and fullerene components within the charge-separating-and charge-transporting film. [1][2][3] Thermal annealing has proven to be the most effective method to control and enhance the phase separation and, thereby, improve the device performance. When annealed at elevated temperatures, the P3HT and fullerene components demix and simultaneously develop crystallinity while maintaining the phase-separated networks. Upon changing the annealing time and/or temperature, the length scale of phase separation evolves and "ripens" in a manner reminiscent of that observed in two-phase systems during spinodal decomposition.[4]We have carried out a focused study of the morphology utilizing an approach not previously applied to BHJ network systems: spatial Fourier-transform analysis of images obtained using transmission electron microscopy (TEM). TEM was used to investigate the phase separation morphology; the digital TEM images were then analyzed by carrying out a spatial Fourier transform of the image intensity to obtain the power spectral density (PSD). PSD has been widely used on digital atomic force microscopy (AFM) images to achieve surface roughness information. [5][6][7] In this report, we introduce spatial Fourier transform and PSD as a method for quantitative analysis of TEM images of the polymer of the BHJ materials used in the fabrication of "plastic" solar cells.Polymer solar-cell devices were fabricated under optimum conditions which have been reported previously.[3] In order to relate device performance to morphology change we made TEM specimens using the same polymer film applied to device fabrication. As shown in Figure 1A and B, TEM images of the films were captured before and after annealing at 150°C for 10 min. The TEM images clearly show the changes in the phase separation morphology before and after annealing. The film shown in Figure 1A was cast from solution and dried at room temperature; the phase separated microstructure can be seen, but it is poorly defined. After annealing the same film at 150°C for 10 minutes, the TEM image shows well-defined phase segregation with a quasi-periodic appearance, as shown in Figure 1B. One can see interconnected dark and bright regions which form an interpenetrating network throughout the entire area of the image. The bright regions are attributed to P3HT-rich domains because the electron scattering density of [6,6]-Phenyl-C 61 butyric acid methyl ester (PCBM) is higher than that of poly(3-hexylthiophene) (P3HT). [8,9] Upon annealing the blend film above the glass transition temperature (T g ) of P3HT (for P3HT, T g ≈ 50°C), the two components demix and the length scale of the phase separated structure evolves with time...

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“…11 On the other hand, in the last years there has been an increasing interest in the analysis of the scaling behavior of the surface roughness and its relationship with the growing mechanisms of the thin films. 16,17 Based on the so-called dynamic scaling theory ͑DST͒, these studies rely on the evolution of the surface roughness with the deposition time and the scale of measurement. The evolution of the roughness ͑␣͒ and growth ͑␤͒ exponents deduced from this analysis provides information about the influence of the different surface processes controlling the thin film growth ͑surface diffusion, surface reactivity, shadowing effects, etc.͒ and, therefore, in the shaping of the surface morphology.…”

Section: Introductionmentioning

confidence: 99%

Relationship between scaling behavior and porosity of plasma-depositedTiO2thin films

et al. 2007

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The growth of TiO 2 thin films prepared by plasma enhanced chemical vapor deposition has been studied by analyzing their roughness with the concepts of the dynamic scaling theory. Differences in the growth and roughness exponents have been found depending on the composition of the plasma by using either O 2 or mixtures Ar+ O 2 as plasma gas and titanium isopropoxide as the precursor. The slope of the representations of the film roughness against the deposition time yielded values of the exponent ␤ of 0.45 and 0.32 for, respectively, thin films prepared with plasmas of O 2 or mixtures Ar+ O 2 . Meanwhile, values of the exponent ␣ of 1.15 and 1.89/0.35 were deduced from the power spectral density representations for the films prepared under these two experimental conditions. These values are congruent with growth processes dominated, respectively, by shadowing or diffusion processes. A columnar microstructure was observed by scanning electron microscopy for the thin films prepared with pure oxygen. Meanwhile, homogeneous films were obtained with mixtures of Ar+ O 2 . The open porosity of the films was determined by measuring water adsorption-desorption isotherms with a quartz crystal monitor. This analysis showed that in the samples prepared with mixtures of Ar+ O 2 the porosity consisted exclusively of micropores ͑d Ͻ 2 nm͒, while in the films prepared with an oxygen plasma there were micro-and meso-pores ͑d Ͼ 2 nm͒. It is concluded that the different growth mechanisms found by just changing the chemistry of the plasma are responsible for the quite distinct microstructures, porosities, and optical properties obtained for the films.

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Analyzing atomic force microscopy images using spectral methods

Cited by 140 publications

References 26 publications

Structure and morphology of Cu/Ni film grown by electrodeposition method: A study of neutron reflectivity and AFM

Structure and morphology of Cu/Ni film grown by electrodeposition method: A study of neutron reflectivity and AFM

Spatial Fourier‐Transform Analysis of the Morphology of Bulk Heterojunction Materials Used in “Plastic” Solar Cells

Relationship between scaling behavior and porosity of plasma-depositedTiO2thin films

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