Papers by Keyword: X-Ray Reflectometry

Abstract: Normal 0 false false false RU X-NONE X-NONE The combination of methods of voltammetry, Raman spectroscopy, and X-ray reflectometry for the first time has been applied for the more comprehensive investigation of interfacial boundaries of GaAs, i.e. determination of phase distribution and thickness of the phase layers. The conditions for the formation of elemental arsenic on a GaAs surface in the process of selective dissolution are discussed. The stability of interfacial boundaries in air has also been studied. The investigations have shown that air storage lead to the oxidation of formed As⁰ and reorganization of GaAs interfacial boundary accompanied by the formation of Ga₂O₃ and As⁰ as a result of a reaction between As₂O₃ and GaAs. The results on interfacial boundaries composition were found to be correlated with the theoretical data. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Обычная таблица"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;}

Abstract: Chemical etching is still preferred to plasma etching in numerous integrated circuits manufacturing steps. Indeed, it enables a better surface smoothness control, which is critical to obtain sufficient carrier mobility. During these steps, photoresist patterns protect underlying materials from etching. It is therefore mandatory to: 1) guarantee photoresist adhesion and keep patterns from being etched away; and 2) prevent surface degradation from etchants penetration down to the photoresist / material interface. To avoid this latter phenomenon, it is therefore crucial to know if etchants penetrate into the photoresist, and at which diffusion rate.

Abstract: The X-ray reflectometry (XR), as a non-destructive method, is a powerful tool in obtaining information about parameters of thin films such as thickness, average density and interface roughness. In this paper Cu/Au, Au/Cu and Cu/Ag multilayer thin films (where the total thickness is less then 1000Å) are presented. The multilayer films are obtained by thermal evaporation in a UHV system, on the silicon substrate. The experimental XR curves contained critical angle and classical Kiessig’s fringes. For these materials the density (), the thickness () and interface roughness () information for every layer separately were calculated. The experimental reflectometry curves were analyzed using the WinGixa programme X’Pert software. The values of layer density show that they are reached in neighbor density and it is connected with the creation of the Cu-Au or Ag-Cu interlayer reached into Cu, Au or Ag, respectively. The analysis of roughness show that there are comparable to roughness of substrate only for 2-3 first layers. Further the roughness of Cu, Au, Ag layers are increasing. The comparison of results show that increasing of Ag an Au roughness is bigger than Cu.

Abstract: Evolution of interdiffused Gaussian-shape nanolayer of Au-Si, formed due to diffusion of Au into Si(111) substrate at ambient conditions, depends strongly on the Si surface pretreatment/passivation conditions. Negligible diffusion in the Au-OSi(111) sample, confirms the strong barrier action of the oxide-layer against diffusion, while large diffusion in the Au-HSi(111) sample compared to that in the Au-BrSi(111) sample suggests that the H-passivated Si(111) surface is more stable. This nature of the Au-Si(111) system is qualitatively similar to that of the Au-Si(001) system but it differs quantitatively. The size, electronegativity and bond-energy of the passivating elements and the number of dangling bonds on the Si surface influence the instability of the Si surface. This instability, parameterized by growth-time of oxide layer alone, can be utilized to tune the amount of diffusion into the sub-surface Si region. The distribution of growth-time and fractional passivated area, which are related to the improper Si surface passivation, are against such control and needs perfection.

Abstract: In the present contribution the results of the high-resolution X-ray diffraction and X-ray glancing-incidence mirror reflection studies of structural characteristics of the quantum-well GaAs/Ga1-xInxAs/GaAs diluted magnetic semiconductors (DMSC) are presented. The influence of the real structure of the samples on their electro-physical properties is discussed.

Abstract: Amorphous silicon on amorphous carbon (a-Si/a-C) multilayers was deposited by RadioFrequency (RF) sputtering. These multilayers were obtained by alternate deposition of a-C and a-Si layers, respectively from graphite and silicon targets of high purity, on crystalline silicon substrates. The RF power and the argon pressure, during the pulverization, were maintained respectively at 250W and 10-2 mbar. The annealing effects, at temperatures of 450°C and 750°C, on the deposited structures were investigated by X-ray reflectometry. The a-Si/a-C interfaces are abrupt before and after annealing at 450°C. The annealing at 750°C leads to a net decrease of both the upper a-Si layer thickness and the total multilayer thickness with a net enhancement of the interfaces reactivity. The upper silicon layer is crystallized after annealing at 750°C.

Abstract: The X-ray reflectivity measurements were used for the analyses of the SiC and SiN thin layers. Density, roughness and the thickness were determined for searching materials. The calculations and simulations were carried out using the WinGixa software. The obtained results show that the studied layers are non-homogenous and there are consist of “sub-layers” rich in Si-C, Si-N, SI-O phases. Moreover, the presence of the main amorphous phase was observed in all searching samples.

Abstract: Pt/AlN multilayered films fabricated by alternative sputtering deposition were characterized by X-Ray Reflectometry and X-Ray Diffraction. As-deposited films have (111) and (001) preferred orientation for Pt and AlN, respectively. The X-Ray Reflectivity profiles are assigned to the total reflection and Bragg reflections due to periodic layer structure. The Bragg peaks are observed at the 2Theta range beyond 15 degree and the peak intensities increase after annealing. The reflectivity of the first order Bragg reflection is approximately 65% and is stable after annealing at 873K. Simulation of the reflectivity profile has shown roughnesses of the Pt/AlN interfaces are below 0.4nm. X-Ray Diffraction revealed the development of film texture and formation of superlattice by annealing. The latter indicates periodicity of film is very high.