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In this paper, the correlation between the electrochromic performance and the surface morphology of the tungsten trioxide (WO 3 ) thin films sputtered by dc reactive magnetron sputtering with widely varying target-substrate distances was investigated. It is found that the optical density change (∆OD) of films is strongly affected by the target-substrate distance. The coloration efficiency (CE) at 633 nm was also found to be sensitive to the target-substrate distance, with 16 cm 2 /C of film sputtered at 6 cm and 50 cm 2 /C at 18 cm. X-ray diffraction showed that the crystal structure of films was amorphous. By using atomic force microscope to identify the surface porosity of the sputtered WO 3 films, we found that the film at longer target-substrate distance was rough, porous, and having a cone-shaped columns morphology, thus offering a good electrochromic performance for opto-switching applications.

This paper reports the growth of single-crystalline silicon carbon nitride (Si 1ϪxϪy C x N y ) films on crystal silicon substrate using C 3 H 8 for carbon source by rapid thermal chemical vapor deposition ͑RTCVD͒. Based on the scanning electron microscope analysis, the Si 1ϪxϪy C x N y films are smooth on the surface and at the Si 1ϪxϪy C x N y /Si interface, which is important for device applications. A model to explain the growing mechanism of the Si 1ϪxϪy C x N y film is being proposed.Silicon carbon nitride (Si 1ϪxϪy C x N y ) film has attracted much attention because of its interesting characteristics and wide range of promising applications. 1 The crystalline Si 1ϪxϪy C x N y possesses several physical properties such as hardness, oxidation resistance, and corrosion resistance that can compete with those of cubic boron nitride. A recent study of Si 1ϪxϪy C x N y compounds shows potential applications for blue or ultraviolet optoelectronic and high temperature microelectromechanical system ͑MEMS͒. 1,2 In the past, the fabrications of Si 1ϪxϪy C x N y films by reactive magnetron sputtering, ion implantation, and plasma-assisted chemical vapor deposition have been reported. 1,3-5 However, these methods grow either rod-shaped crystals, mixtures of crystalline and amorphous, or pure amorphous Si 1ϪxϪy C x N y films. No smooth surface morphology and uniform crystalline structure, which are important for applications in high voltage or high temperature electronic devices, have been found.In this study, a cubic single-crystal Si 1ϪxϪy C x N y (c-Si 1ϪxϪy C x N y ) film has been successfully synthesized, for the first time, using C 3 H 8 as the carbon source in a rapid thermal chemical vapor deposition ͑RTCVD͒ system under a wide variety of deposition conditions. The C 3 H 8 gas is selected for the purpose of low cost and the wide utility in industrial manufacture. Moreover, the RTCVD system is adopted for its capability of rapid temperature increases and higher temperature that provide the absorbed pieces a higher surface mobility to form a smoother interface and better microstructure. 6 In addition, Auger electron spectroscopy ͑AES͒, scanning electron microscopy ͑SEM͒, and transmission electron microscopy ͑TEM͒ are employed to characterize the composition and the structure of the films. Based on the analysis, a mechanism of growing cubic structure c-Si 1ϪxϪy C x N y film is being proposed. Fabrication and MeasurementThe Si 1ϪxϪy C x N y films were grown on Si͑100͒ wafers with resistivity of 4-10 ⍀ cm, using a homemade RTCVD system with horizontal fused quartz tube as furnace. The heat source is ultraviolet ͑UV͒ halogen lamps with high energy density. The temperature of the substrate is measured by an optical pyrometer. After chemical cleaning, the substrates were immediately loaded into the reaction tube, and then the system was pumped down to about 10 Ϫ7 Torr. Then follows the process sequence as illustrated in Fig. 1 to deposit the films; ͑A͒ The substrates were held at 900°C for 10 min to remove native oxide la...

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Characterization of amorphous hydrogenated carbon nitride films prepared by plasma-enhanced chemical vapor deposition using a helical resonator discharge