Spectroscopic in situ diagnostics of boron nitride film growth in plasma-enhanced deposition

The development of in situ diagnostics of the most important species and reactions in the plasma and/or on the surface during thin-film growth is one of the current topics in plasma-enhanced vapor deposition. In situ thin film diagnostic methods which could be used in plasma processing are restricted due to the presence of electrons and ions. The advantages and disadvantages of different applicable methods will be discussed. The spectroscopic in situ control of boron nitride film growth is presented as an example of surface modification in low-temperature, low-pressure plasma processing. The growth of cubic and hexagonal boron nitride is observed by polarized infrared reflection spectroscopy in absorption and ellipsometric configurations as well as by single-wavelength ellipsometry in the visible spectral range. Modeling of the experimental results gives detailed information on growth conditions and internal stress of the films. Received: 8 August 2000 / Accepted: 12 December 2000 / Published online: 3 April 2001     

Characterization of solid standards prepared by freeze‐drying

Solid standards prepared by freeze‐drying consistently showed a high degree of homogeneity. The freezing process, completed in fractions of a second, preserves the original homogeneous distribution of the dopants, and the subsequent sublimation step would minimize any disturbance. Compared to those prepared by conventional methods such as blending and spiking, freeze‐dried standards exhibited superior lateral distribution and better uniform depth distribution. There is, however, a concentration constraint for achieving homogeneity. At 5% doping, segregation was observed in both lateral and depth distribution. Many tungsten standards doped with 10–28 elements ranging from 10 to 200 ppm were successfully prepared and used as controls for a number of analytical techniques including glow discharge mass spectrometry (GDMS) and d.c.‐arc optical emission spectroscopy (OES). Copyright © 2009 John Wiley & Sons, Ltd.     

Synthese und Strukturuntersuchungen von Ba2H[α-FeO4W12O36] · 26 H2O

Synthesis and Structure Studies of Ba₂H[α-FeO₄W₁₂O₃₆] · 26 H₂O The heteropolyanion compound Ba₂H[α-FeO₄W₁₂O₃₆] · 26 H₂O (I) crystallizes in the tetragonal space group P4 n2 with the lattice parameters a = 12.398(6), c = 18.721(6) Å; Z = 2; D_x = 4.128 g · cm^?3. The structure was solved on a twinned crystal from 1029 observed reflections and refined to an index R of 7.6%. The calculations were done by means of a modified ORFLS-programme by Eitel and Bärnighausen. The heteropolyanion [α-FeO₄W₁₂O₃₆]^5? has the well known α-Keggin structure. The average distance of the four central oxygen atoms to the Fe^III position (0, 0, 0) is 1.84 Å. The angles ? O? Fe? O are 112.3° (4X) and 103.9 (2X), respectively, which leads to an disphenoidal distortion of the FeO₄ tetrahedron. The powder and single crystal ESR spectra of I show the anisotropy of the Fe^III fine structure transition 1/2 ? ?1/2. The Mößbauer spectra confirm the tetragonal distortion of the central FeO₄ tetrahedron (quadrupole splitting Δ ≈ 0.50 mm · s^?1).     

Röntgenographische Hochtemperaturuntersuchung der Thermischen Zersetzung von Dodekawolframatoborsäure

Investigation on the Thermal Degradation of 12-Tungstoboric Acid by Means of X-ray Heating Photographs By means of X-ray Guinier investigation of 12-tungstoboric acid hexahydrate H₅[BO₄W₁₂O₁₂] · 6H₂O at room temperature a monoclinic lattice was determined, being in disagreement with the literature. The LSQ-refinement of parameters of the monoclinic C-lattice give a = 1.728 nm, b = 1.215 nm, c = 1.216 nm, b? = 135° 34′, Z = 2, d_exp. = 5.44 g cm^?3, d_calcd. = 5.52 g cm ^?3. From X-ray heating patterns (heating rate: 4°C/min, atmosphere: air) the formation of a new monoclinic phase at 185°C was found, being stable till 270°C. From 270–420°C exist a bad crystalline phase and from 420–840°C a monoclinic phase: a = 0.532 nm, b = 0.389 nm, c = 0.522 nm, b? = 91° 09′. Above 840°C a tetragonal phase is formed with a diagram typical for pure WO₃. The relationship between the modifications is discussed.     

Simulation of boron nitride sputtering process and its comparisonwith experimental data

In the paper, TRIM and TRIDYN simulation codes were used to simulate the sputtering processes of boron nitride (BN) films during bombardment of ions. The TRIM and TRIDYN codes are applicable to the simulation of sputtering processes of different target materials with amorphous and polycrystalline structure. The results of the simulations are compared with experimental data. The sputtering experiments of polycrystalline hexagonal BN (h-BN) and cubic BN (c-BN) films were performed in a Commonwealth Scientific Corporation (CSC) 38-cm ion beam source device. The comparison of calculated and experimental results indicated that a) the experimental sputtering yields of h-BN and c-BN films bombarded with Ar⁺ ions versus the angle of incidence are in reasonable agreement with the calculated results; b) the sputtering yields of h-BN and c-BN bombarded with Ar⁺ are nearly of the same values versus the angle of incidence-preferential sputtering of h-BN was not found; c) the calculated sputtering. Yields of BN as a function of Ar⁺ ion energy are very sensitive to values of the surface binding energy (SEE); and d) surface binding energy between 2 and 3 eV for BN appears to be reasonable for the simulation of sputtering process of h-BN and c-BN films     

Röntgenographische Kristallstrukturuntersuchung von Magnesiumperrhenat-tetrahydrat Mg(ReO4)2 · 4 H2O

Crystal Structure of Magnesium Perrhenate Tetrahydrate Mg(ReO₄)₂ · 4 H₂O The crystal structure of Mg(ReO₄)₂ · 4 H₂O was determined from single-crystal X-ray diffractometer data. The compound is triclinic, space group P1, with lattice parameters a = 769.2, b = 702.6, c = 646.9 pm, α = 108.279, β = 92.388, γ = 120.418°, Z = 1, ?_calcd. = 3.58 g · cm^?3, ?_exp. = 3.62 g · cm^?3. The structure was solved in anisotropic approximation from 2990 observed reflections and refined to an index R of 7.4%. The rhenium atom is tetrahedrally, the magnesium atom octahedrally coordinated.     

Untersuchung der thermischen Zersetzung von Aluminium-dodekawolframatosilicat

Investigation on the Thermal Degradation of Aluminium-12-Tungstosilicate The dehydration of aluminium-12-tungstosilicate AlH[SiO₄W₁₂O₃₆] · 29 H₂O gives the anhydrous salt at 440°C. By means of X-ray heating patterns, thermal analysis, and i.r. spectroscopy the formation of the new phase 1/2 Al₂O₃ · SiO₂ · 12 WO₃ (I) at 500°C is observed, stable at room temperature. Above 800°C from I tetragonal W₃, Al₂(WO₄)₃, and amorphous SiO₂ are formed. Amorphous SiO₂ crystallizes to high-temperature cristobalite at 1000°C. High-resolution ²⁷Al NMR (MAS-technique) is used to determine the coordination number of aluminium in the different phases.     

Das erste KEGGIN-Anion mit tetraedrischer. Kupfer(II)—Sauerstoff-Koordination: [α-Cu0,4(H2)0,6O4W12O36]6−

The First KEGGIN-Anion with Tetrahedral Coordination of Copper(II)-Oxygen: [α-Cu_0,4(H₂)_0.6O₄W₁₂O₃₆]^6? The solution of the Cu^II-containing heteropolyanion was prepared starting from an aqueous solution of Na₂WO₄, adjusting to pH 5–6 by adding slowly a solution of Cu(NO₃)₂ in HNO₃. The addition of the corresponding amount of N(CH₃)₄Br to the concentrated solution led to the crystallization of the greenish-yellow mixed crystals (TMA)₆[α-Cu_0.4(H₂)_0.6O₄W₁₂O₃₆] · 9 H₂O. After repeated recrystallization it has been investigated by chemical, spectroscopic (IR/Raman, UV, ¹⁸³W/¹H-NMR, ESR) and X-ray diffraction methods (monoclinic; space group P2₁; a = 13.117(4), b = 21.466(4), c = 13.223(3) Å, β = 91.60°; Z = 2; D_c = 3.041 g · cm^?3; R = 8.0%). The distances of the four “tetrahedral” oxygen atoms to the position (0, 0, 0) range from 1.67 to 1.93 Å. The alternative occupation of the central KEGGIN position with copper(II) and two protons, respectively, accounts for the different distances. The prepared solid solution represents the first example for the tetrahedral copper(II)-oxygen coordination in any heteropolyanion compound.