Jan-Otto Carlsson

Use of atomic layer epitaxy for fabrication of Si/TiN/Cu structures

The properties of titanium nitride deposited by atomic layer epitaxy (ALE) using three different deposition processes, i.e., TiI4+NH3, TiCl4+NH3 and TiCl4+Zn+NH3, as a diffusion barrier between cop ...

Chemical vapour deposition of boron carbides I: Phase and chemical composition

Abstract Different boron carbides were deposited by chemical vapour deposition in a cold-wall reactor from a reaction gas mixture of BCl 3 , CH 4 and H 2 . The influences of vapour composition, temperature and total pressure on the phase and chemical composition were investigated. One orthorhombic, two tetragonal and two types of rhombohedral boron carbide phases were identified. Diffraction data and chemical composition of the carbides are given. From a comparison of the results from deposition experiments and thermodynamic calculations it was concluded that the deposition took place far from equilibrium.

The solution hardening of β-rhombohedral boron

Abstract Solid solutions of transition metals in β-rhombohedral boron have been investigated using X-ray techniques and microhardness measurements. The variation of microhardness with unit cell volume is discussed.

Corrosion behaviour of Ti/TiN multilayer coated tool steel

The corrosion behaviour of Ti/TiN multilayer coated tool steel has been investigated by potentiodynamic measurements in 0.1 M H2SO4 and compared with single layer coatings of Ti and TiN, respectively. All the coatings had a total thickness of about 1 mu

Chemical vapour deposition of boron carbides in the temperature range 1300–1500 K and at a reduced pressure

Abstract An experimental chemical vapour deposition (CVD) phase diagram was determined for the CVD of boron carbides in the temperature range 1300–1500 K at a total pressure of 50 Torr. Boron trichloride, methane and hydrogen were used as the reaction gases. The reactor was of the cold-wall type. The phase diagram contains four crystalline and two amorphous phases. In addition to the previously known phases, a new phase (orthorhombic), which is closely related to the tetragonal boron carbides, was found. The initial growth rates of the carbides and the factors influencing their growth rates were investigated. Finally characteristic morphologies of the carbides are illustrated.

CHEMICAL VAPOR-DEPOSITION OF THE SUPERCONDUCTING YBA2CU3O7-X PHASE USING HALIDES AS METAL SOURCES

It is shown for the first time that the superconducting YBa2Cu3O7−x phase can be deposited by chemical vapor deposition using the halide precursors YCl3, BaI2, and CuCl as metal sources and an O2/H2O gas mixture. Sintered calcium stabilized zirconia plates were used as substrates. The superconductor was obtained upon deposition without the need for post‐annealing. An ideal (001) texture was always found to prevail.

Deposition rate and rate-limiting steps in the chemical vapour deposition of boron in a closed system

Abstract The deposition rate of boron in a closed chemical vapour deposition system was investigated. Various methods for the determination of deposition rates are outlined. Values for the apparent activation energy of the deposition process were found to lie in the range 100–1000 kJ mol−1. An apparent activation energy value of 100 kJ mol−1 indicates that the deposition rate is controlled partly by diffusion and partly by surface kinetics. It is concluded that, in the range 121–218 kJ mol−1, the process is limited by two concurrent surface kinetics mechanisms. Apparent activation energy values higher than 218 kJ mol−1 indicate that nucleation becomes an important rate-limiting step. At approximately 1000 kJ mol−1 the process is completely controlled by nucleation. Finally, the origin of various morphologies of the boron deposit is discussed in connection with a schematic kinetics curve.

Chemical vapour deposition of Cu2O and CuO from CuI and O2 or N2O

Thin films of CuO and Cu2O were deposited from CuI as the copper source and O2 or N2O as the oxygen source. If O2 was used, both CuO and Cu2O were obtained. Cu2O was deposited at low O2 partial pressures (Po2 < 0.2 Torr) in a long isothermal hot wall chemical vapour deposition (CVD) reactor (T=500 °C). The CuO phase was obtained at a certain position in the CVD reactor and a sudden maximum in the deposition rate was then reached. The maximum was attributed to a change in the deposition mechanism upon the formation of CuO. When I2 was added to the reaction gas mixture, the maximum disappeared and the deposition rate increased. The formation of CuO was also investigated thermodynamically. For higher [I2]/[CuI] ratios, the CuO phase was stable, even at a low O2 pressure. Cu2O films were also deposited with N2O as the oxygen source. At 650 °C and with an excess of CuI, the deposition rate was found to be controlled by the decomposition of N2O. Above a linear gas flow velocity of 70 cm s−1, the deposition rate was constant, which indicated a surface-controlled process.

Atomic Layer Epitaxy of Tungsten Oxide Films Using Oxyfluorides as Metal Precursors

Atomic layer epitaxy (ALE) of WO 3 from WF 6 and H 2 O has been studied. These precursors were found to yield very low deposition rates. This was attributed to a poor adsorption of WF 6 on the oxide surface. Attempts to increase the adsorption of the metal source by in situ generation of tungsten subfluorides were unsuccessful due to severe etching problems. Our results, however, showed that different WO x F y compounds are good candidates for ALE of WO 3 . The oxyfluorides were generated in situ by etching of tungsten oxide lumps with WF 6 at temperatures up to 600°C. No analysis of the generated WO x F y precursors was carried out, but thermodynamic calculations suggest that the main etch products should be WOF 4 and WO 2 F 2 . An ALE process based on the in situ generated oxyfluorides and H 2 O as precursors was found to yield monoclinic WO 3 films at substrate temperatures as low as 200°C. The deposition rate at this temperature was about 0.8 A/deposition cycle. The films deposited at 200°C contained small amounts (<2 atom %) of fluorine.

Extensions of the quartz-crystal-microbalance technique

Abstract The high mass sensitivity of the quartz-crystal microbalance is explained by the very high acceleration of the particles on the surface of the quartz resonators. The sensing properties of quartz resonators in contact with a solid, liquid or gas medium are explained within the energy-transfer model. The use of the quartz-crystal microbalance is extended up to the Curie point (573 °C) by employing a dual resonator. Standing compressional waves, generated by a shear-mode quartz resonator in a liquid or by a compressional-mode quartz resonator in a gas, are used for sensing small changes in the composition of a liquid or gas, respectively.