Thin Films|13 Article(s)
Preparation of Zr-based Thin Film Metallic Glass and Determination of Its Optical Constant
Man-yu WU, and Shui-ping HUANG
The aim of this paper is to obtain the optical constants of the thin film metallic glass in the visible and near-infrared region. Zr-based (ZrCuNiAl(64.13∶15.75∶10.12∶10%at)) thin film metallic glass was prepared on Si substrate using vacuum magnetron sputtering technology at first, then the ellipsometric parameters of the sample at three different angles of incidence were measured by spectroscopic ellipsometry. The optical constants and thickness of the film in the visible and near-infrared region were obtained by fitting the measured ellipsometric parameters using the Drude-Lorentz two-oscillator model. Moreover, the thickness of the sample was also measured by grazing incidence X-ray reflection to verify the reliability of the measurement results of the ellipsometer. The results show that the thicknesses of the sample measured by the two methods are consistent. The Drude-Lorentz two-oscillator model can describe the optical properties of the Zr-based thin film metallic glass in the visible and near-infrared region well. In the visible and near-infrared region, both of Ψ and Δ decrease with increasing incident angle; the real parts of the dielectric constants are negative and decrease with increasing wavelength; the imaginary parts of the dielectric constants are positive and increase with increasing wavelength. The refractive index of the sample is obviously smaller than the extinction coefficient. The refractive index has its maximum at 1 070 nm, and the extinction coefficient has an inflection point around 1 070 nm. It follows that thin film metallic glass has the optical properties of both general metal and glass. The investigatedresults of this paper will be helpful for the investigation and measurement of the optical properties of Zr-based and the other kinds of thin film metallic glass.
Acta Photonica Sinica
  • Publication Date: Oct. 15, 2020
  • Vol. 49 Issue 10 1031001 (2020)
Research on Infrared Anti-reflection Thin Film Devices with Compatibility of Electromagnetic Shielding
Jian WANG, Jun-qi XU, Jun-hong SU, Yang LI, and Yun-yun SHI
Photolithography mask and thermal evaporation deposition technology were used to fabricate a thin film devices compatible with electromagnetic shielding infrared window, which could realize the device to possess the efficient anti-reflection of infrared signals in the band of 3~5 μm and shield electromagnetic signals in the frequency band of 12~18 GHz. The cross-sectional symmetric metal grid microstructures which met requirements were prepared on the double-sided polished Si substrate by photolithography mask and vacuum thermal evaporation deposition technology, the highly efficient anti-reflection infrared in the 3~5 μm band was prepared by ion beam assisted electron beam thermal evaporation deposition technology. In order to improve the transmittance of the metal grid further, an infrared anti-reflection film was deposited on the metal grid coating with a cycle g of 550 μm and different line widths. Results show that the peak transmittance of the infrared anti-reflection film at 3~5 μm is 99.8% and the average transmittance is 99.3% through the measurement of vacuum Fourier infrared spectrometer. The electromagnetic shielding effectiveness in the 12~18 GHz frequency band of the metal grid was measured by vector network analyzer, and obtained the overall electromagnetic shielding efficiency of the compatible electromagnetic shielding infrared window thin film device in the 12~18 GHz band is better than 27 dB, the peak transmittance in the 3~5 μm infrared band is 86.3%, and the average transmittance is 86.1%. On the premise of ensuring the electromagnetic shielding efficiency is unchanged(≥27 dB), the transmittance of the metal grid films has increased by 37.6%(the grid cycle g is 550 μm, line width 2a is 30 μm). The improvement of shielding efficiency can be achieved either by adjusting the cycle and line width of the grid, or selecting a substrate material with lower resistivity.
Acta Photonica Sinica
  • Publication Date: Oct. 15, 2020
  • Vol. 49 Issue 10 1031002 (2020)
Development of Polycarbonate High Strength Ultra-low Reflectivity Film
Dong-mei LIU, Bo-yang WEI, Xiu-hua FU, Jing ZHANG, Suo-tao DONG, and Shuang LI
In order to reduce the problem of image quality degradation caused by stray light in the optical system, polycarbonate is used as the substrate and the electron beam ion assisted method is used to prepare the ultra-low attenuation reflective film in visible band. Vacuum annealing method was used to reduce the thermal tensile stress caused by the increase of substrate temperature in the coating process, and MATLAB software was used to fit and analyze the stress of the material. By studying the ion source deposition process, the problem of film cracking was solved. MATLAB simulation was used to adjust the control parameters of Proportion Integration Differentiation(PID) controller , so as to stabilize the film-forming rate and solve the problem of spectral drift caused by thickness error. The results show that the absolute reflectance of the film is less than 0.15% at 430 ~ 700 nm.
Acta Photonica Sinica
  • Publication Date: Dec. 25, 2020
  • Vol. 49 Issue 12 216 (2020)
Structure and Luminescence Properties of Eu3+ and Dy3+ Co-implanted AlN Films
Hai MA, Xiao-dan WANG, Xiang LI, Dan WANG, Hong-min MAO, and Xiong-hui ZENG
Acta Photonica Sinica
  • Publication Date: Aug. 25, 2020
  • Vol. 49 Issue 8 0831001 (2020)
Infrared Indium Oxide Hf-doped Transparent Conductive Films
Feng TIAN, Ran BI, Wen-yuan ZHAO, Feng-bo HAN, Ya-dan LI, Chuan-tao ZHENG, and Yi-ding WANG
High-quality indium Hf-doped oxide (IHfO) films were prepared on quartz and ZnSe substrates by RF magnetron sputtering and annealing. The doping ratio of In2O3:HfO2 was 98wt.%:2wt. %. The composition of the film and the photoelectric properties of the 3~5 μm infrared band were tested and analyzed. The effects of annealing temperature, film thickness and oxygen flow rate on the properties of the film were analyzed. The results of XRD, SEM and XPS show that the prepared IHfO film has the stereo-structure of indium oxide. The doping of germanium does not affect the growth direction of indium oxide, but it leads to the decrease of lattice spacing, and the new hybridization of germanium and indium electrons track. The FTIR test results show that the transmittance of IHfO film in the 3~5 μm band decreases with the increase of annealing temperature, and the film deposited on the ZnSe substrate has a more stable transmittance. When the film thickness is 100 nm, the average transmission rate in the 3~5 μm is around 68%. The Hall Effect test results show that with the increase of oxygen flow rate, the resistivity of IHfO film increases gradually, the carrier concentration decreases, and the Hall mobility changes little. The analysis shows that grain boundary scattering is the main factor affecting the mobility of IHfO film. The optimal resistivity of the film is 3.3×10-2Ω·cm when the oxygen flow rate is 0.3 sccm. Compared with the commercial visible-band Indium Tin Oxide (ITO) thin films, the IHfO thin films prepared in this paper can be better applied in gas detection, infrared guidance and other related fields in the 3~5 μm infrared band.
Acta Photonica Sinica
  • Publication Date: Sep. 01, 2020
  • Vol. 49 Issue 9 0931001 (2020)
Light Trapping Enhancement of Composite Rough Surface ZnO:Al Gratings in Thin Film Silicon Solar Cells
Ren-chen LIU, Jing LU, He-ping CHENG, Zhao-ming LIANG, and Yang LIU
This paper discussed the influence of composite rough surface aluminum-doped zinc oxide (ZnO:Al) gratings on light trapping efficiency of thin film silicon solar cells. Rough surface was characterized by correlation length (lcor) and average height (have), and superimposed on a one-dimension sine ZnO:Al grating with 980 nm period and 160 nm groove depth. The short-circuit current was higher when front electrode AZO grating had smaller lcor and larger have. As lcor=0.01, short-circuit current raised with the increase of have value, from 21.93 mA/cm2 of have=0.05 to 23.80 mA/cm2 of have=0.80. When used as back electrode, the short-circuit current decreased with the increase of have, from 25.50 mA/cm2 of have=0.05 to 24.81 mA/cm2 of have=0.80. Composite rough surface ZnO:Al grating and non-rough surface ZnO:Al grating were fabricated by chemical etching and direct current sputter respectively. Reflectivity results showed that total reflection of composite rough surface ZnO:Al grating (8.3%) was 1.9% lower than that of non-rough surface ZnO:Al grating (10.2%), and specular reflection of composite rough surface ZnO:Al grating (4.7%) was 2.1% lower than that of non-rough surface ZnO:Al grating (6.8%). Rigorous coupled wave method was used to simulate reflection of ZnO:Al grating with and non- rough surface. Results further confirmed that composite rough ZnO:Al grating was more suitable for front electrode of thin film solar cells due to its better anti-reflection effect and could obtain a larger short-circuit current. Non-rough surface ZnO:Al grating could reflect more photons back to silicon absorption layer due to its higher reflection and was more suitable for back electrode.
Acta Photonica Sinica
  • Publication Date: Sep. 01, 2020
  • Vol. 49 Issue 9 0931002 (2020)
Preparation and Optoelectronic Properties of Semi-transparent Cu2O/ZnO Heterojunction
Jin-zhu LI, Ai-ling TIAN, Bing-cai LIU, Hong-jun WANG, and Xue-liang ZHU
In order to study the semi-transparent thin film solar cell with better material stability, use direct current magnetron sputtering technique to deposit cuprous oxide(Cu2O) thin film and zinc oxide(ZnO) thin film, forming the Cu2O/ZnO heterojunction. By using scanning electron microscope, X-ray diffractometer, raman spectrometer, thin film measurement instrument and solar simulator, the influence caused by Cu2O layer prepared under different Ar/O2 gas flow ratio on material properties, optical properties and photoelectric properties of heterojunction is studied. Results show that the Cu2O/ZnO heterojunctions produced under the certain Ar/O2 gas flow ratios have certain photoelectric conversion ability under the standard simulated sunlight of AM1.5, which can be used as the energy conversion unit of the semi-transparent solar cell.
Acta Photonica Sinica
  • Publication Date: Aug. 25, 2020
  • Vol. 49 Issue 8 0831003 (2020)
Study on Passivation of Monocrystalline Silicon by Tandem Hydrogenated Amorphous Silicon Film
Yueke DING, and Shihua HUANG
Studies on the passivation of monocrystalline silicon wafers by using plasma enhanced chemical vapor deposition for the deposition of monolayer intrinsic hydrogenated amorphous silicon films show that increasing the hydrogen dilution ratio is beneficial to reducing the defects in the films and enhancing the passivation effect. Excessive hydrogen dilution ratio can lead to the epitaxial growth of amorphous silicon on the silicon wafer surface and reduce the passivation effect. Annealing results in the increase of the degree of crystallization of amorphous silicon and the reduce of passivation effect. Meanwhile, annealing improves the quality of thin films and changes the way of H bonding and enhances the passivation effect. Therefore, the best passivation effect of monolayer hydrogenated amorphous silicon can be obtained only at appropriate hydrogen dilution ratio and annealing temperature. In order to improve the passivation effect of amorphous silicon film on silicon wafer, tandem intrinsic amorphous silicon film with high and low hydrogen dilution ratio is used to passivate silicon wafer. Therefore, the epitaxial growth of amorphous silicon on the silicon wafer surface can be avoided by stacking amorphous silicon thin films with high hydrogen dilution ratio on the thin films with low hydrogen dilution ratio. In the annealing process, the hydrogen in the film with high hydrogen dilution ratio diffuses into the film with low hydrogen dilution ratio, effectively passivating the suspension bonds on the surface of amorphous silicon and monocrystalline silicon, and improving the interface quality of amorphous silicon/silicon wafer. After the tandem passivation of the silicon wafer, the effective minority carrier lifetime is 7.36 ms, and the implied open-circuit voltage is 732 mV.
Acta Photonica Sinica
  • Publication Date: Mar. 25, 2021
  • Vol. 50 Issue 3 194 (2021)
Study on Properties of Fluorine-oxide Composite Films
Yun-yun SHI, Jun-qi XU, and Jun-hong SU
SiO2/YF3 and TiO2/YF3 composite films were prepared by SiO2, YF3, TiO2 single-component materials respectively, the changes of optical, mechanical and laser damage resistance properties of the composite films were explored. Two kinds of fluorine-oxide composite films with a mixing molar ratio of 1:1 were prepared by controlling the deposition rate of the materials during evaporation through dual-source co-evaporation technique, the refractive index, extinction coefficient, transmission characteristics, surface morphology and roughness of the composite films were investigated, and laser damage resistance performance was studied. The results show that the refractive indexes of SiO2/YF3 and TiO2/YF3 composite films are 1.478 7 and 1.864 6(wavelength 550 nm) respectively, which are between the single-component materials(YF3 1.493 6, SiO2 1.465 1, TiO2 2.048 3), and all present normal dispersion distribution; the results of ZYGO interference measurement show that the stress value of SiO2/YF3 film is 1.9 GPa, which is larger than the 0.4 GPa of the single-component materials SiO2 and YF3 but less roughness; the stress value of TiO2/YF3 film is 0.8 GPa, which is smaller than the 3.9 GPa stress of TiO2 but larger than YF3, both of them show a more obvious stress adjustment effect. The laser-induced damage threshold of SiO2/YF3 composite film is 9.2 J/cm2, which is 2.2% higher than single-component SiO2 and 39.2% higher than YF3; the laser-induced damage threshold of TiO2/YF3 is 7.8 J/cm2, for the single-component TiO2 film, it increases by 85.6%, compared with YF3 by 17.4%. The fluorine-oxide composite films are deposited by dual-source co-evaporation technology with small absorption and adjustable film refractive index; SiO2/YF3 and TiO2/YF3 composite films are better than single-component materials in resisting laser damage; the doping of YF3 can significantly reduce the stress of the single TiO2 material, but the stress of SiO2/YF3 is larger than that of single-component SiO2 and YF3 films.
Acta Photonica Sinica
  • Publication Date: Aug. 25, 2020
  • Vol. 49 Issue 8 0831002 (2020)
Influence of Substrate Temperature on Properties of ZnSe Thin Films Deposited by Electron-beam Evaporation
Guangyu ZHAO, Li XU, Jie FAN, Jiabin ZHANG, Yunping LAN, Yonggang ZOU, and Xiaohui MA
In order to study the influence of substrate temperature on the microstructure and optical properties of ZnSe thin films, a single layer of ZnSe thin films was prepared on K9 glass substrate by electron beam evaporation. By studying the X-ray diffraction spectrum, transmission spectrum characteristics, surface morphology and roughness of the thin film, the variation rules of the microstructure and optical properties of the thin film under different substrate temperatures were analyzed. The experimental results show that the ZnSe films prepared in the range of substrate temperature from 20℃ to 200℃ are all single crystal films with (111) crystallographic texture. With the increase of substrate temperature, the kinetic energy obtained by atoms on the substrate increases, resulting in the increase of grain size, internal strain and dislocation density of the films. The optical properties of thin films are also different at different substrate temperatures. With the increase of substrate temperature, the refractive index and extinction coefficient decrease, the optical band gap increases, and the surface roughness of thin films decreases. It is concluded that the decrease of refractive index is caused by the increase of the proportion of the pores in the film, and the decrease of extinction coefficient is caused by the increase of crystallinity and the reduction of internal defects.
Acta Photonica Sinica
  • Publication Date: Jun. 25, 2021
  • Vol. 50 Issue 6 209 (2021)