Spectroscopic ellipsometry study of CVD molybdenum oxide films: effect of temperature

The optical properties of CVD MoO₃ films were studied by ellipsometry in the spectral range 280–820 nm. The films were deposited on silicon substrates by pyrolytic decomposition at atmospheric pressure of Mo(CO)₆ at 150 and 200 °C. To optimize the film structure, annealing was performed at temperatures of 300 and 400 °C. The refractive index for as-deposited MoO₃ films varies within 1.8–2.2 and the optical band gap energies in the range 2.87–2.98 eV. After annealing, the latter values slightly increase to 2.85–3.05 eV, depending on the annealing temperature. The band gap energies are typical for a polycrystalline material. Peaks in the spectral dependence of the absorption coefficient were observed. Their position and intensity are found to be affected by the process temperature. Electronic Publication     

Structure and optical properties of CVD molybdenum oxide films for electrochromic application

Vibrational and optical properties of MoO₃ thin films have been studied by Raman and infrared spectroscopy. The films were deposited onto Si substrates at a temperature of 150 °C by chemical vapor deposition of Mo(CO)₆ at atmospheric pressure and different amounts of oxygen in the reactor. The Raman and IR spectral analyses show that the as-deposited films are in general amorphous. Post-deposition annealing at 300 and 400 °C leads to crystallization and the MoO₃ film structure is a mixture of orthorhombic and monoclinic MoO₃ modifications. Transformation of the monoclinic crystallographic modification to a thoroughly orthorhombic layered structure is observed for films heated at temperatures above 400 °C. Electronic Publication     

Der chemische Transport von Titangermaniden

Chemical Vapor Transport of Intermetallic Systems. 8. Chemical Transport of Titaniumgermanides By means of chemical vapor transport using iodine as transport agent in the System Ti/Ge the compounds TiGe₂ and Ti₅Ge₃ have been prepared in form of single crystals. Unexpectedly the phase Ti₆Ge₅ could not be deposited from the vapor phase. The experiments show in contrast to the literature that Ti₆Ge₅ is at 700 °C thermodynamic unstable. Chemical vapor transport is a suitable method to determine coexistence conditions of intermetallic compounds.     

Zum chemischen Transport von Bismutoxidhalogeniden BiOX (X = Cl,Br, I) mit Halogen,Halogenwasserstoff sowie Wasser und Bestimmung der Molwärmen von BiOX

Chemical Transport of Bismuth Oxide Halides BiOX (X = Cl, Br, I) with X₂, HX and H₂O, and Determination of the Molar Enthalpies of BiOX By comparison of calculated and experimental chemical transport behaviour of BiOX (X = Cl, Br, I) with X₂, HX, and H₂O it was shown, that we understand the transport of BiOCl, BiOBr and BiOI with X₂ and HX in terms of the well known gaseous spezies in the systems. The existence of gaseous complexes Bi(OH)₂X is be concluded from high transport rates of BiOX with water, and their enthalpies and entropies were derived. The molar enthalpies and standard entropies of BiOX were determined by low temperature C_p measurements. (Data see Inhaltsübersicht)     

Chemischer Transport fester Lösungen. 17 [1] Der Chemische Transport von ZnS und CdS mit Phosphor — die Mischphase ZnS:P

Chemical Vapor Transport of ZnS and CdS with Phosphorus — ZnS:P mixed Crystals The volality of ZnS and CdS is enlarged in the presence of Phosphorus vapor. This is due to the formation of PS(g). By means of chemical vapor transport (1000 → 900 °C) using phosphorous as transport agent ZnS:P mixed crystals (sphalerit type) have been prepared. Density measurements on these mixed crystals show that interstitial zinc atoms are the consequence of the substitution of sulfur by phophorus atoms.     

Der Chemische Transport von Mischkristallen im System FeS/MnS/ZnS

Chemical Vapor Transport of Solid Solutions. 7. Chemical Vapor Transport of FeS/MnS/ZnS Mixed Crystals By means of chemical vapor transport using iodine as transport agent (900 → 800 °C) it is possible to prepare in the quasiternary system FeS/MnS/ZnS the mixed crystals (Fe,Mn,Zn)S (sphalerite and wurtzite type), (Fe,Mn)S(ZnS) (NaCl type) and FeS(MnS,ZnS) (NiAs type) in form of single crystals. Based on the composition of these phases the phase diagram for the system FeS/MnS/ZnS at 800 °C was drawn up. The incongruent transport process leads to the accumulation of ZnS in the crystallization zone.     

Zur Kristallstruktur von CuInMo2O8

On the Crystal Structure of CuInMo₂O₈ . Single crystals of CuInMo₂O₈ were prepared and investigated by X-ray work. It shows monoclinic symmetry, space group C—C2/c; a = 9.549 Å, b = 11.529 Å, c = 5.000 Å; β = 91.38(2)°, Z = 4. CuInMo₂O₈ represents a LiYbW₂O₈ related structure, characterised by zigzag-chains of MoO₆-octahedrons and octahedrons around copper and indium. With respect to LiFeW₂O₈ the single and three-valent ions are in opposite distribution. There are strong evidence for molybdenum in lowered oxidation state.     

Der Chemische Transport von Kupfer/Gallium‐ und Silber/Gallium‐Phasen

Chemical Vapor Transport of Intermetallic Systems. 10. Chemical Transport of Copper/Gallium and Silver/Gallium Phases The solid solution of gallium in copper and the ζ‐ and the γ‐phase can be prepared by CVT‐methods using iodine as transport agent. The solid solution of gallium in silver and the ζ‐phase and the ζ′‐phase can also prepared by CVT‐methods. Thermodynamic calculations allow to understand why these phases can be prepared by this manner.     

Der chemische Transport von Kupfergermaniden und Kupfersiliciden

Chemical Vapor Transport of Intermetallic Systems. 9 Chemical Transport of Copper Germanides and Copper Silicides By means of chemical vapor transport using iodine and bromine as transport agents in the system Cu/Ge the compounds Cu₃Ge (ϵ and ϵ₁), Cu₅Ge (ζ) and copper‐rich mixed crystals Cu(Ge) have been prepared in form of single crystals. Thermodynamic considerations allow to understand the CVT process, especially the unexpected low temperatures. Copper silicides can be prepared under similiar conditions. They are extremely disordered. Their crystallographic characterisation was therefore impossible.