Electrochromic properties of tungsten-titanium oxide films

The last decade has seen great in electrochromic (EC) technology for smart windows and displays. In this study, WTiOx films formed from TiO2 and WO3 were deposited onto ITO glass with a sheet resistance of 10 Omega cm and on silicon substrates, by pulsed magnetron sputtering using a W and Ti alloy target. The films were deposited at plasma powers 100, 200, 300, 400 and 500 W using a gaseous Ar (150 sccm)/O2 (50 sccm) mixture; the working pressure was fixed at 5E-2 torr. The film thickness increased with the plasma power. However, increasing the plasma power yielded a more crystalline structure with poorer electrochromic properties. The influence of Ti doping and plasma power on the structural, optical and electrochromic properties of the WTiOx thin films was studied. WTiOx films grown at various plasma powers of under 400 W were amorphous. Deposition of films at 400 W yielded the optimal electrochromic properties, with high optical modulation, high coloration efficiency and the lowest color memory effect at wavelengths 400, 550 and 800 nm. An XPS study indicated that Ti can stabilize the valence state of W6+. The improvements caused by the doping with Ti were tested: an optical density (OD) of close to 0.85 and a maximum delta T (%) at 400 nm of 25.8%, at 550 nm of 52.5% and at 800 nm (in the near-IR region) of 62.4%.     

Effect of oxygen plasma treatment on bonding states for columnar structured a-CNx thin films prepared by reactive sputtering

Amorphous carbon nitride (a-CN) thin films were deposited on silicon single crystal substrates by rf-reactive sputtering method using a graphite target and nitrogen gas. The substrate temperature was varied from room temperature (RT) to 853 K. After deposition, the effect of oxygen plasma treatment on bonding structures of the film surface has been studied by using an oxygen discharge at 16 Pa and rf power of 85 W. The chemical bonding states and film composition were analyzed by X-ray photoelectron spectroscopy (XPS), while film thickness was obtained from scanning electron microscopy (SEM) and ellipsometer. XPS study revealed that the films have NO₂ and NO₃ bonding structures when the films are deposited at temperatures higher than 673 K. After exposure to oxygen plasma, carbon in the film surface was etched selectively and this phenomenon was observed in all films. In contrast, the surface concentration of nitrogen was ket at constant values before and after oxygen plasma treatment. The NO₃ bonding state had dramatically increased after oxygen plasma treatment for films deposited at higher deposition temperatures. The film surfaces have been observed to change the function from hydrophobic to hydrophilic after oxygen plasma treatment.     

Structure and morphology of phenylsilanes polymer films synthesized by the plasma polymerization method

Phenylsilanes were deposited by r.f. glow discharge to investigate the relationship between the synthesis conditions (r.f. power, synthesis time and monomer) and the structure and morphology of plasma-polymerized films. The film deposited at 2.0 W consisted of polycarbosilane-like main chains and side chains corresponding to the monomer structure. The film deposited at higher r.f. power consisted of a polycarbosilane-like main chain with more cross-links and less aromatic groups. The films synthesized at 2.0 W from phenylsilane had many submicrometre sized particles on the surface, but the films synthesized from phenylsilanes with methyl groups had few particles and smooth surfaces. The films deposited at higher r.f. power had many particles on their surfaces. The infrared spectra of methylphenylsilane polymer films were independent of the synthesis time, but film surface morphology changed from a smooth surface into a granular surface with an increase in the synthesis time. © 1998 Chapman & Hall     

Preparation, characterization and femtosecond time-resolved optical Kerr effect of plasma polybenzonitrile derivative films

Plasma-polymerized thin films based on two benzonitrile derivatives, aminobenzonitrile (ABN) and nitrobenzonitrile (NBN), were prepared by r.f. glow discharge techniques. Fourier transform infrared (FTIR) and UV-Visible absorption spectra revealed that extensively conjugated C N double bonds have been formed during plasma polymerization in both derivatives. The films formed are transparent and dark brown in color. Morphological study using a field emission microscope (FEM) indicated that fine and homogeneous films could be obtained at comparatively low discharge powers. The femtosecond time-resolved optical Kerr effect was used to measure the third-order optical nonlinearity. A unique ultrafast response and non-resonant optical Kerr effect of two polybenzonitrile derivative films were observed. Furthermore, the effects of polymer molecular structures on the non-linear optical properties were also tentatively discussed.     

Investigation of deposition rate and structure of pulse DC plasma polymers

In this study, hydrophobic plasma polymer films were prepared from perfluorohexane with saturated linear structure and octafluorotoluene with a cyclic unsaturated structure. Hydrophilic plasma polymer film was prepared from acrylic acid with an unsaturated linear structure. The film deposition rates were compared through in-situ laser interferometer measurement and correlated them with the precursor structure and the deposition parameters. The chemical structure and the surface energy of the films were also investigated with FTIR and contact angle measurement. The results showed that the deposition rate increased with the discharge power. Otherwise, the deposition rate relied on the structure of the precursors to a large extent. The deposition rate of octafluorotoluene is 7 times the deposition rate of perfluorohexane and 5 times the deposition rate of acrylic acid at the same deposition parameters. So a high deposition rate could be obtained for the precursors with cyclic and unsaturated structures. For the pulse discharge of acrylic acid, there existed a maximum deposition rate for a certain pulse frequency. But it was found that the pulse frequency had greater effects on the structure of the plasma films than on the deposition rate. As the pulse frequency decreased, more CHO and O---C=O groups were found in the deposited film of acrylic acid. And the pulse discharge at low power could keep more aromatic ring in octafluorotoluene plasma film than continuous discharge at high power. This explained the phenomenon that the surface energy of octafluorotoluene plasma film deposited by the low power pulse discharge was lower than that of the film deposited by the high power continuous discharge and showed to be more hydrophobic.     

Structural and optical properties of amorphous oxygenated iron boron nitride thin films produced by reactive co-sputtering

Amorphous oxygenated iron boron nitride (a-FeBN:O) thin films were prepared by reactive radio-frequency (RF) sputtering, from hexagonal boron nitride chips placed on iron target, under a total pressure of a gas mixture of argon and oxygen maintained at 1 Pa. The films were deposited onto silicon and glass substrates, at room temperature. The power of the generator RF was varied from 150 to 350 W. The chemical and structural analyses were investigated using X-ray photoelectron spectroscopy (XPS), energy dispersive of X-ray and X-ray reflectometry (XRR). The optical properties of the films were obtained from the optical transmittance and reflectance measurements in the ultraviolet-visible-near infrared wavelengths range. XPS reveals the presence of boron, nitrogen, iron and oxygen atoms and also the formation of different chemical bonds such as Fe-O, B-N, B-O and the ternary BNO phase. This latter phase is predominant in the deposited films as observed in the B 1s and N 1s core level spectra. As the RF power increases, the contribution of N-B bonds in the as-deposited films decreases. The XRR results show that the mass density of a-FeBN:O thin films increases from 2.6 to 4.12 g/cm³ with increasing the RF power from 150 to 350 W. This behavior is more important for films deposited at RF power higher than 150 W, and has been associated with the enhancement of iron atoms in the film structure. The optical band gap decreases from 3.74 to 3.12 eV with increasing the RF power from 150 to 350 W.     

Comparison of their electrical,optical, and electrochemical properties of as-grown plasma polymerized organic thin films by PECVD

Plasma polymerized organic thin films have been deposited on Si(100), glass and metal substrates at 25∼100 °C using thiophene and toluene precursors by plasma enhanced CVD method. In order to compare physical and electrochemical properties of the as-grown thin films, the effect of the RF (13.56 MHz) plasma power in the range of 30∼100 W and the deposition temperature on the corrosion protection efficiency and optical property were mainly studied in this work. Corrosion protection efficiency (P_k), which is one of important factors for corrosion protection in the interlayer dielectrics of microelectronic devices application, provided an increasing tendency with increasing RF power. The highest P_k value of plasma polymerized toluene film (85.27% at 70 W) was higher than that of the plasma polymerized thiophene film (65.17% at 100 W). The result of contact angle measurement showed that the plasma polymerized toluene films have more hydrophobicity than that of the plasma polymerized thiophene films.     

Residual stress on nanocrystalline silicon thin films deposited under energetic ion bombardment by using internal ICP-CVD

Nano/microcrystalline silicon thin films were deposited using an internal-type, inductively coupled, plasma-chemical vapor deposition (ICP-CVD) at room temperature by varying the bias power to the substrate. The structural characteristics of the deposited thin film were investigated. The deposition rate was increased by the application of a small RF bias power of 30 W (12.56 MHz), but was then decreased as the bias power was increased above 30 W. In addition, the application of bias power generally increased the residual compressive stress, which was attributed to the increased defect formation in the thin film due to the formation of interstitial atoms. The crystalline volume fraction was also decreased with increasing bias power. However, in the low bias power range of 0-60 W, the compressive stress in the deposited thin film was in the range of − 34 to − 77 MPa, which was lower than the residual stress in the range of − 150 to − 1050 MPa that is observed for the nano/microcrystalline silicon thin films deposited by capacitively coupled plasma.     

Low-temperature preparation of phosphorus doped μc-Si:H thin films by low-frequency inductively coupled plasma assisted chemical vapor deposition

The phosphorus doped n-type hydrogenated microcrystalline silicon (n-μc-Si:H) thin films are prepared, at the two low substrate temperatures of room temperature and 200 °C, through a low-frequency inductively coupled plasma assisted chemical vapor deposition. The effect of the substrate temperature on the structural properties of the thin films, such as the X-ray Diffraction (XRD) patterns and the Raman spectra, is studied. The XRD measurements show that the diffraction orientations of the thin films present an obvious change when the radio frequency power is increased from 1300 W to 2300 W. The Raman spectra of the thin films deposited at room temperature unambiguously present a phase transition from the amorphous structure to microcrystalline structure whereas no structural phase transition is observed for the thin films deposited at 200 °C. The effect of the substrate temperature on the crystalline volume fraction of the thin films presents a large difference for the radio frequency power in the range of 1300 W-1700 W, while the difference becomes small when the power is increased from 1700 W to 2300 W. The deposition rate and the radio frequency power-sheet resistance curve of the thin films deposited at room temperature are obviously different from those of the thin films prepared at 200 °C. It is attributed to the joint effect of the radio frequency power and substrate temperature on the doping concentration. The electron energy distribution function of the species in the chamber is mainly distributed in a low energy range.     

直流磁控溅射法制备掺钛氧化锌透明导电薄膜

采用直流磁控溅射法在室温水冷玻璃衬底上制备出高质量的掺钛氧化锌(ZnO:Ti)透明导电薄膜,研究了溅射功率对ZnO:Ti薄膜结构、形貌和光电性能的影响,结果表明,溅射功率对ZnO:Ti薄膜的结构和电阻率有显著影响.XRD表明,ZnO:Ti薄膜为六角纤锌矿结构的多晶薄膜,且具有c轴择优取向.当溅射功率为130W时,实验制备的ZnO:Ti薄膜的电阻率具有最小值9.67×10~(-5)Ω·cm.实验制备的ZnO:Ti薄膜具有良好的附着性能,可见光区平均透过率超过91%.ZnO:Ti薄膜可以用作薄膜太阳能电池和液晶显示器的透明电极.     

A study on the electrical and optical characteristics of IGZO films

The electrical and optical properties of InGaZnO (IGZO) thin films were studied in the research. It was found that all the films deposited at room temperature exhibit amorphous structures. A better film quality was obtained at a lower pressure with sputtering ambiance. The RF power toward the IZO target was constant at 125 W; the RF power toward the Ga₂O₃ target varied from 0 to 70 W. A best IGZO film with corresponding resistivity, carrier concentration, and mobility is 7.94 × 10^?4 Ω-cm, 1.68 × 10²⁰ cm^?3, and 47 cm²/V-s, respectively. Due to the doping of gallium in the IGZO film, it led to a lower resistivity than that of the IZO film. A blue shift effect of the film was also observed in the doping of gallium to the IGZO film. The H₂ plasma effects toward the IGZO were also observed.     

Characteristics of hydrogenated silicon thin film deposited by RF-PECVD using He–SiH4 mixture

Nanocrystalline silicon thin films (nc-Si:H) were deposited using He as the dilution gas instead of H₂ and the effect of the operating pressure and rf power on their characteristics was investigated. Especially, operating pressures higher than 4 Torr and a low SiH₄ containing gas mixture, that is, SiH₄(3 sccm)/He(500 sccm) were used to induce high pressure depletion (HPD) conditions. Increasing the operating pressure decreased the deposition rate, however at pressures higher than 6 Torr, crystallized silicon thin films could be obtained at an rf power of 100 W. The deposition of highly crystallized nc-Si:H thin film was related to the HPD conditions, where the damage is decreased through the decrease in the bombardment energy at the high pressure and the crystallization of the deposited silicon thin film is increased through the increased hydrogen content in the plasma caused by the depletion of SiH₄. When the rf power was set at a fixed operating pressure of 6 Torr, HPD conditions were obtained in the rf power range from 80 to 100 W, which was high enough to dissociate SiH₄ fully, but meantime low enough not to damage the surface by ion bombardment. At 6 Torr of operating pressure and 100 W of rf power, the nc-Si:H having the crystallization volume fraction of 67% could be obtained with the deposition rate of 0.28 nm/s.     

Characteristics of hydrogenated silicon thin film deposited by RF-PECVD using He-SiH4 mixture

Nanocrystalline silicon thin films (nc-Si:H) were deposited using He as the dilution gas instead of H₂ and the effect of the operating pressure and rf power on their characteristics was investigated. Especially, operating pressures higher than 4 Torr and a low SiH₄ containing gas mixture, that is, SiH₄(3 sccm)/He(500 sccm) were used to induce high pressure depletion (HPD) conditions. Increasing the operating pressure decreased the deposition rate, however at pressures higher than 6 Torr, crystallized silicon thin films could be obtained at an rf power of 100 W. The deposition of highly crystallized nc-Si:H thin film was related to the HPD conditions, where the damage is decreased through the decrease in the bombardment energy at the high pressure and the crystallization of the deposited silicon thin film is increased through the increased hydrogen content in the plasma caused by the depletion of SiH₄. When the rf power was set at a fixed operating pressure of 6 Torr, HPD conditions were obtained in the rf power range from 80 to 100 W, which was high enough to dissociate SiH₄ fully, but meantime low enough not to damage the surface by ion bombardment. At 6 Torr of operating pressure and 100 W of rf power, the nc-Si:H having the crystallization volume fraction of 67% could be obtained with the deposition rate of 0.28 nm/s.     

Hydrogen plasma transport and deposition of films from a solid boron source

Thin boron films were produced on Si substrates from a solid boron source and a hydrogen plasma. The plasma was generated using a 13.56 MHz generator and films were deposited with a forward radio frequency (RF) power of 2.0 kW. At pressures from 0.931–2.26×102 Pa under high hydrogen concentrations a capacitively coupled plasma (CCP) was observed whereas at low hydrogen concentrations an inductively coupled plasma (ICP) was observed. The films were predominantly deposited with an ICP but in one case a film was deposited using a CCP discharge. The deposited films consisted primarily of boron, but they also contained oxygen and silicon. The films were amorphous at 225 and 350°C, but revealed X-ray diffractions at 475°C. It was concluded that the hydrogen concentration, RF plasma power and surface temperature as well as the plasma-boron source interactions strongly influenced the film thickness and composition.     

BN薄膜的制备及BPXN1-X薄膜的紫外光敏特性

采用热丝和射频等离子体辅助化学气相沉积方法(HF-PECVD),以单晶硅为衬底在低温(< 500℃)条件下沉积氮化硼(BN)薄膜材料.通过傅立叶变换红外光谱(FTIR)、 X射线衍射(XRD)及扫描电镜(SEM)对薄膜样品的组成和结构进行了分析,探讨了温度和等离子体对沉积BN薄膜的影响.此外,用紫外-可见光分光光度计(UV)测试了石英衬底上生长磷掺杂氮化硼(BPXN1-X)薄膜样品的紫外吸收特征,分析了磷掺杂对 BN光学能隙的调节作用以及 BPXN1-X薄膜在紫外空间探测领域的应用前景.结果表明,以单晶硅和光学石英玻璃为衬底在低温条件下用 HF-PECVD方法可以沉积较高质量的 BN薄膜,BN的光学能隙宽度通过磷的掺杂可以得到连续调节,在紫外空间光探测领域具有很大的应用潜力.     

Plasma oxidation of electron beam evaporated cadmium thin films

Thin films of pure cadmium have been deposited using electron beam evaporation technique. Effect of radio frequency (RF) plasma oxidation on structural, optical and electrical properties of cadmium thin films has been investigated. It was found that the RF plasma treatment affects on the physical properties of the oxidized cadmium films. Transmittance values of 87% in the visible region and 90% in the near infrared region have been obtained for cadmium oxide (CdO) film oxidized at a plasma-processing power of 600 W. The optical energy gap, E_g, was found to increase as the RF plasma-processing power increases. The resistivity values of 3 × 10^− 3 and 5 × 10^− 3 (Ω cm) have been obtained for CdO films oxidized at RF plasma-processing powers of 550 and 600 W respectively.     

Factors affecting the adhesion of microwave plasma deposited siloxane films on polycarbonate

The effects of a radiofrequency oxygen plasma pretreatment and residual water content in the substrate on the adhesion of microwave plasma deposited tetramethyldisiloxane thin films on Bisphenol-A polycarbonate (BPA-PC) were investigated. Samples were characterised using a crosshatch adhesion test, optical and electron microscopy, and X-ray photoelectron spectroscopy. It was found that the use of a low power (5 W) and low treatment time (0.1 s) oxygen plasma can improve adhesion while greater treatment times (1–30 s) and higher oxygen plasma powers (40 W) resulted in a decreased level of adhesion. In addition, it was shown that a BPA-PC water content greater than 90 ppm resulted in rapid adhesion failure of deposited films at the substrate–plasma polymer interface during outdoor weathering. All films degraded substantially when exposed to environmental weathering, indicating ageing reactions within the plasma polymer films themselves, and at the bulk polymer–coating interface.     

Experimental investigations of semi-crystalline plasma polymerized poly(3-octyl thiophene)

Plasma polymerized thin film of conducting poly(3-octylthiophene) was deposited at room temperature by plasma enhanced chemical vapor deposition method using (3-octylthiophene) monomer as precursor. The radio frequency (RF: 13.56 MHz, power supply: 30 W) was applied at constant argon gas pressure for the formation of plasma. Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), X-ray diffractometry (XRD) and high resolution transmission electron microscopy (HRTEM) have been done for the as grown films. As reported in literature polythiophenes prepared by rf plasma polymerization are highly crosslinked and amorphous. However, in present investigations, well defined crystalline regions have been observed by HRTEM investigations and have been correlated with X-ray diffraction data. The observed crystallinity is attributed to controlling the parameters of the synthesis.     

直流磁控溅射功率对溅射生长GZO薄膜光电性能的影响

本文采用直流磁控溅射沉积系统在玻璃基底上沉积镓掺杂氧化锌(GZO)薄膜,将溅射功率从120W调整到240W,步长为30W,研究功率变化对GZO薄膜的晶体结构、表面形貌、光学性能和电学性能的影响。结果表明,溅射功率对GZO薄膜电阻率有显著的影响。溅射功率为210W时薄膜呈现最低电阻率为3.31×10~(-4)Ω·cm,可见光波段平均光学透光率接近84%。随着溅射功率的增加,薄膜表面形貌和生长形态发生较大变化,并直接得到具有一定凸凹不平的微结构,GZO薄膜的致密性先增加后降低。     

Effect of the oxygen pressure on the photoluminescence properties of ZnO thin films by PLD

ZnO thin films on Si(111) substrate were deposited by laser ablation of Zn target in oxygen reactive atmosphere; Nd-YAG laser with wavelength of 1064 nm was used as laser source. The experiments were performed at laser energy density of 31 J/cm², substrate temperature of 400 °C and various oxygen pressures (5–65 Pa). X-ray diffraction was applied to characterize the structure of the deposited ZnO films and the optical properties of the ZnO thin films were characterized by photoluminescence with an Ar ion laser as a light source using an excitation wavelength of 325 nm. The influence of the oxygen pressure on the structural and optical properties of ZnO thin films was investigated. It was found that ZnO film with random growth grains can be obtained under the condition of oxygen pressure 5–65 Pa. It will be clearly shown that the grain size and the formation of intrinsic defects depend on the oxygen partial pressure and that high optical quality of the ZnO films is obtained under low oxygen pressure (5 Pa, 11 Pa) conditions.