A. Bath

Iteratively derived optical constants of MoO3 polycrystalline thin films prepared by CVD

Abstract Polycrystalline MoO 3 thin films have been prepared by oxidation at high temperature of molybdenum compound layers deposited by chemical vapour deposition (CVD) from molybdenum hexacarbonyl Mo(CO) 6 . In this paper is presented the experimental procedure to prepare polycrystalline MoO 3 coatings by annealing at various temperatures and in various annealing environments of “black molybdenum” or “reflective molybdenum” thin films. From X-ray diffraction measurements the structure of the films has been determined. The optical constants n and k of films were calculated by numerical iteration, using the Fresnel laws and dispersion relations of n and k . From these results the optical gap E g has been deduced. All the samples exhibited the electrochromic effect.

Optical properties of boron nitride thin films deposited by microwave PECVD

Abstract Hexagonal boron nitride thin films (h-BN) were deposited by microwave PECVD on various substrates (silicon, quartz, glass…), and were analysed by infrared, UV visible and microraman spectroscopies. The interpretation of the IR spectra recorded at oblique incidence allowed us to determine the preferential orientation of the c -axis of the h-BN films. The influence of the deposition conditions on the orientation is studied as a function of the plasma power. The optical constants in the infrared are also given by the Kramers–Kronig method.

Formation and characterisation of c-BN thin films deposited by microwave PECVD

Abstract Boron nitride thin films were deposited on silicon substrates at low temperature by plasma-enhanced chemical vapour deposition (PECVD), with a microwave surfatron launcher. An organometallic compound, borane-dimethylamine, was used as the boron precursor. To promote the growth of the cubic phase, a negative self-bias was applied to the sample holder by means of a 13.56-MHz RF signal. A very high fraction of c-BN was achieved as revealed by infrared spectrometry. The assignation of the characteristic TO absorption band was ascertained by the observation of its LO associated mode by performing the IR transmission spectra at non-normal incidence. The deposited films are well adherent and do not delaminate even after 6 months in the atmosphere, and they exhibit a very low roughness, as observed by atomic force microscopy.

Influence of annealing treatment on the physical properties of c-BN films deposited by IBAD technique

Boron nitride films prepared by ion beam assisted deposition (IBAD) have been studied. The presence of the cubic phase was checked by HRTEM microscopy. The adhesion of the films was very poor and without a thin boron sublayer, the films delaminated just after deposition. In an attempt to improve the adhesion, post deposition annealing was performed. The structure and the stress of the films were followed by infrared spectroscopy (FTIR). Annealing carried out on c-BN films shows a thermal threshold of stability around 950 °C. These effects are discussed according to the proportion of the cubic phase present in the film.

Electrical properties of MIS structures with BN insulating layer

Abstract Electrical properties of MIS structures with a BN insulating layer on InP substrate are investigated by means of capacitance-voltage characteristics. These characteristics show the conventional shape for MIS structures. The BN:1nP interface is studied by deep-level transient spectroscopy using the DLS-82E spectrometer. The measured spectra exhibit non-conventional behavior, with the gradual increase of the filling pulse duration and the filling pulse amplitude, which can be explained by means of dipolar relaxation effects.