Papers by Keyword: Reflectometry

Abstract: Silicon carbide (SiC) MOSFETs are widely utilized in power device applications for their numerous advantages, and the device’s properties can be further optimized through the implementation of trench structures. The formation of the trench structure is a multi-step process, in which it is important to monitor the result of each step and ensure that the structure meets the desired requirements. OCD (optical critical dimension) metrology can provide a fast, non-destructive solution for this purpose. In this article, an OCD analysis of structures at two different process steps is presented and compared with the results from the electron microscopy images. OCD results show high sensitivity to the geometrical dimensions of the structure and produce a good correlation with the electron microscopy images. This metrology can provide a means to detect subtle structural differences without causing any damage to the sample.

Abstract: An application of compact benchtop X-ray diffractometer for investigation of thin film semiconductor structures was demonstrated. A depth-dependent qualitative phase analysis of multilayer polycrystalline CuInGaSe₂-based solar cell structure was performed. The independent goniometer allowed determination of residual stress values in the molybdenum layer of the solar cell. Grazing-incidence X-ray diffractometry was used to estimate polycrystallinity degree of AlN layers grown by molecular beam epitaxy and correlate it with the growth temperature. X-ray reflectometry measurement were also performed for nucleation AlN layer.

Abstract: The morphology and optical properties of nanostructured diamond films affected by the two-step deposition process with changing CH₄ concentration were investigated. The CH₄ concentration was 1% for the first step and 2% for the second step. The films were prepared by chemical vapor deposition in a microwave plasma reactor with a CH₄/H₂ gas mixture. Nanocrystalline columnar-structured diamond film with lowering of sp²-bonded carbon content was achieved by the two-step deposition process. Unlike that of the single-step process with 1%CH₄, the two-step process promoted the morphology to more uniform and smoother film. The two-step process increased the higher grain boundary as well as decreased the sp²-bonded carbon content in the film, as compared with the single-step process with 2%CH4_{Subscript text}.

Abstract: The article intends to introduce the authors’ experimental study on adsorption behaviour of chitosan and poly(acrylic acid) solution on silica by reflectometry. pH effect on adsorption-desorption of Chitosan and interaction with poly(acrylic acid) polyelectrolyte multilayer on silica has been studied. Builting multilayer formation on silica by 100ppm chitosan and 25ppm Poly(acrylic acid) solution with reflectometer. Effect of ionic strengths and molecular weight of chitosan have been discussed and we built 4 layers chitosan and 3 layers PAA and check BSA adsorption and stability. Atomic force microscopy measurement has been measured in the experiment. The results show adsorption kinetics, adsorbed mass plateau values, and reversibility of the layer formation which is typical for adsorption of strongly charged polyelectrolytes onto oppositely charged surfaces.

Abstract: Optical reflectometry is applied as a tool for studying single and simultaneous adsorption of a carbohydrate, a nonionic surfactant, and a protein, For the nonionic surfactant poly(ethylene oxide) alkyl ether on a silica surface the adsorption process is fast and reversible, and the maximum adsorbed amount was 2.45 mg•m^-2. Also, the effect of pH on the adsorption of chitosan on silica, and its interaction with C₁₂EO₅ have been studied. The maximum adsorbed amount was obtained for pH ≥6.8 (0.80 mg•m^-2). Changes in surface functionality upon adsorbing C₁₂EO₅ on a chitosan layer and the protein, bovine serum albumin, are reported. The results are discussed in terms of adsorption kinetics, adsorbed mass plateau values, and reversibility of layer formation.

Abstract: Reflectometry technique has been successfully applied to investigate the correlation between the porosity and optical property (refractive index) of the ordered mesoporous thin film deposited on silicon wafer substrates. The measured optical spectra were simulated by the Effective Medium approximation model. The reflectometry technique has been found to be appropriate for the measurement of thickness of thin films as well as thick layer films. The mesoporous silica films prepared from tri-block copolymer (F-127) as a surfactant and polypropylene oxide as a swelling agent were subsequently exposed to the ammonia vapors to enhance thermal stability and shrinkage minimization of the film that results in increased film thickness.