Xingfang Hu

Structural analysis and microstructural observation of SiCxNy films prepared by reactive sputtering of SiC in N2 and Ar

Abstract In this paper, the amorphous silicon carbonitride (SiC x N y ) films were prepared by radio frequency (RF) magnetron reactive sputtering using sintered SiC target. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectrometer (FTIR) were used for structural characterization of the films. The results revealed the formation of complex networks among the three elements (Si, C and N) and the existence of different chemical bonds in the SiC x N y films such as CN, CN CN, SiC and SiN. The stoichiometry of the as-deposited films was found to be close to SiCN. Atomic force microscopy (AFM) observation showed a very smooth surface morphology of the as-deposited films, which was proved to be amorphous by high-resolution electron micrography (HREM) and selected area diffraction (SAD) and remained very stable even after exposure to electron bombardment.

Structural, morphological and electrochromic properties of Nb2O5 films deposited by reactive sputtering

Abstract Nb 2 O 5 films were prepared successfully by DC reactive sputtering process. The relationships among structural, morphological and electrochromic properties were studied using XRD, AFM, AES and cyclic voltammograms. Results show that the films deposited on heated substrates are composed of columnar TT-Nb 2 O 5 microcrystalline with many grain-to-grain boundaries. These structural characteristics provide films strong electrochemical stability, high Li + insertion/extraction reversibility and good electrochromic properties. DC reactive sputtered Nb 2 O 5 films are colorless in bleached state and brownish gray in colored state and may be a promising candidate for the application in electrochromic devices.

Study on Raman spectra of electrochromic c-WO3 films and their infrared emittance modulation characteristics

Abstract Polycrystalline tungsten oxide films with good electrochemical stability were prepared by dc reactive sputtering method. The Raman spectra of these films show that the W 6+ ions were reduced to W 5+ with the co-intercalation of Li + ions and electrons. Intercalated electrons entered extended states of crystalline tungsten oxide and caused infrared reflectance variation, therefore, the emissivity of WO 3 /ITO/glass can be reversible modulated between 0.261 and 0.589.

Preparation of silicon carbide nitride thin films by sputtering of silicon nitride target

Amorphous silicon carbide nitride thin films were synthesized on single crystal silicon (0 0 1) substrates by rf reactive sputtered a silicon nitride target in methane and argon atmosphere. The effects of sputtering parameters such as target voltage in the range of 1.6‐3.0 kV on the optical properties were studied by a Cary 500 UN-VIS-NIR spectrophotometer and Bio-Rad FTS 185 FTIR spectrometer. The results showed that the deposition rate reached maximal at the target voltage of 2.5 kV. The refractive index, n, decrease with increase of target voltage except the sample deposited on 1.6 kV. Moreover, the maximal proportion of Si‐C and C‐N bond achieved at the target voltage of 2.5 and 2.0 kV, respectively. It reflects that the bonding configuration can be tailored by adjusting the target voltage. # 2001 Published by Elsevier Science B.V.

Mechanical properties of silicon carbonitride thin films

Silicon carbonitride thin films,were synthesized by reactive rf sputtering a silicon carbide target in nitrogen and argon atmosphere, or sputtering a silicon nitride target in methane and argon atmosphere, respectively. The Nanoindentation technique (Nanoindenter XP system with a continuous stiffness measurement technique) was employed to measure the hardness and elastic modulus of thin films. The effects of sputtering power on the mechanical properties are different for the two SiCN thin films. With increasing sputtering power, the hardness and the elastic modulus decrease for, the former but increase for the latter. The tendency is similar to the evolution trend of Si-C bonds in SiCN materials. This reflects that Si-C bonds provide greater hardness for SiCN thin films than Si-N and C-N bonds.

Study on the crystallization behavior of amorphous carbon nitride films

Abstract Amorphous carbon nitride films were first prepared by DC reactive magnetron sputtering, followed by heat treatment under protective nitrogen. The ensuing thermal effects were analyzed by DTA-TG, XRD and XPS. The results showed that heat treatment above 1100°C could induce the transition from an amorphous to a crystalline state of carbon nitride films. Apparent diffraction peaks of α-C 3 N 4 appeared in the XRD spectra of samples heat-treated at 1180°C. XPS results further supported the analysis of crystallization of the films after heat treatment.

Thermal Analysis on the Amorphous Carbon Nitride Prepared by Reactive Magnetron Sputtering

The differential thermal analysis-thermogravimetry-mass spectroscopy (DTA-TG-MS) study on the thermal stability of CNx prepared by magnetron sputtering was carried out under Ar atmosphere. The results show that the decomposition process could be divided into two stages. One spans from room temperature (RT) to 800°C. The nitrogen loss as well as the weight loss in the a-CNx could be attributed to the evaporation of C+(m/z=12), CN+(m/z=26), O2+(m/z=32), CO2+(m/z=44), NO2+(m/z=46), and C2N2+(m/z=52), as detected by mass spectroscopy. The other is above 800°C, during which the breakage of C–N bonds and the oxidation of C and N mainly accounts for the weight loss. The weight loss of a-CNx is 7% for the first stage and 42.8% for the second, suggesting the a-CNx to be more stable at low temperature.

Sputtering deposition and optical properties of SiCxNy films

In this paper, the SiCxNy films were prepared by RF magnetron sputtering with SiC target. The influences of the basic process parameters on the deposition rate and optical properties were studied. The results revealed the formation of a complex network among Si, C and N. The deposition rate decreased with increasing partial pressure of nitrogen. The increase of N2 flux resulted in the wider optical gap. The greater the sputtering power, the higher the deposition rate and the narrower the optical band gap.