Microwave electron cyclotron resonance plasma enhanced chemical vapor depositionwas used to grow silicon dioxide films on crystalline silicon substrate for planar optical waveguides.The relationship between plasma par...Microwave electron cyclotron resonance plasma enhanced chemical vapor depositionwas used to grow silicon dioxide films on crystalline silicon substrate for planar optical waveguides.The relationship between plasma parameters and deposition rates was investigated, and the influ-ence of radio frequency substrate bias on properties of SiO2 films was also preliminarily studied.X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, scanning electron mi-croscopy, atomic force microscopy and elllipsometry were used to characterize the deposited films,showing that SiO2 films with good structural and optical properties prepared at low temperaturehave been achieved. They can basically meet the requirements of integrated optical waveguides.展开更多
Fe2O3/SiO2 nano-composite films were prepared by sol-gel technique combining heat treatment in the range of 100-900 ℃. The particle size was observed by FE-SEM. Optical properties of the films were investigated by UV...Fe2O3/SiO2 nano-composite films were prepared by sol-gel technique combining heat treatment in the range of 100-900 ℃. The particle size was observed by FE-SEM. Optical properties of the films were investigated by UV-visible spectra. Structural and magnetic characteristics were investigated through FT-IR and VSM. The transparency of the Fe2O3/SiO2 nano-composite films decreased with the content of the Fe2O3. Water and organic solvent in the films were evaporated with heat treatment, so the transparency of the films was enhanced under high temperature. It is also found that the saturation magnetization （Ms） of the films increases with the temperature. As the content of the Fe2O3 increases, when the content of the Fe2O3 is around 30wt%, the Ms of the films has a maximum value.展开更多
[SiO2/FePt]5/Ag thin films were deposited by RF magnetron sputtering on the glass substrates and post annealing at 550 ℃ for 30 min in vacuum. Vibrating sample magnetometer and X-ray diffraction analyser were applied...[SiO2/FePt]5/Ag thin films were deposited by RF magnetron sputtering on the glass substrates and post annealing at 550 ℃ for 30 min in vacuum. Vibrating sample magnetometer and X-ray diffraction analyser were applied to study the magnetic properties and microstructures of the films. The results show that without Ag underlayer [SiO2/FePt]5 films deposited onto the glass are FCC disordered; with the addition of Ag underlayer [SiO]FePt]5/Ag films are changed into L10 and （111） mixed texture. The variation of the SiO2 nonmagnetic layer thickness in [SiO2/FePt]5/Ag films indicates that SiO2-doping plays an important role in improving the order parameter and the perpendicular magnetic anisotropy, and reducing the grain size and intergrain interactions. By controlling SiO2 thickness the highly perpendicular magnetic anisotropy can be obtained in the [SiO2 （0.6 nm）/FePt （3 nm）]5/Ag （50 nm） films and highly （001）-oriented films can be obtained in the [SiO2 （2 nm）/FePt （3 nm）]5/Ag （50 nm） films.展开更多
Total dose effects and single event effects on radiation-hardened power vertical double-diffusion metal oxide semiconductor（VDMOS） devices with composite SiO2-Si3N4 film gates are investigated.The relationships amon...Total dose effects and single event effects on radiation-hardened power vertical double-diffusion metal oxide semiconductor（VDMOS） devices with composite SiO2-Si3N4 film gates are investigated.The relationships among the important electrical parameters of the samples with different thickness SiO2-Si3N4 films,such as threshold voltage,breakdown voltage,and on-state resistance in accumulated dose,are discussed.The total dose experiment results show that the breakdown voltage and the on-state resistance barely change with the accumulated dose.However,the relationships between the threshold voltages of the samples and the accumulated dose are more complex,and not only positively drift,but also negatively drift.At the end of the total dose experiment,we select the group of samples which have the smaller threshold voltage shift to carry out the single event effect studies.We find that the samples with appropriate thickness ratio SiO2-Si3N4 films have a good radiation-hardening ability.This method may be useful in solving both the SEGR and the total dose problems with the composite SiO2-Si3N4 films.展开更多
Nano metal-particle dispersed glasses are the attractive candidates for nonlinear optical material applications. Au/SiO2 nano-composite thin films with 3 vol% to 65 vol% Au are prepared by inductively coupled plasma s...Nano metal-particle dispersed glasses are the attractive candidates for nonlinear optical material applications. Au/SiO2 nano-composite thin films with 3 vol% to 65 vol% Au are prepared by inductively coupled plasma sputtering. Au particles as perfect spheres with diameters between 10 nm and 30 nm are uniformly dispersed in the SiO2 matrix. Optical absorption peaks due to the surface plasmon resonance of Au particles are observed. The absorption property is enhanced with the increase of Au content, showing a maximum value in the films with 37 vol% Au. The absorption curves of the Au/SiO2 thin films with 3 vol% to 37 vol% Au accord well with the theoretical optical absorption spectra obtained from Mie resonance theory. Increasing Au content over 37 vol% results in the partial connection of Au particles, whereby the intensity of the absorption peak is weakened and ultimately replaced by the optical absorption of the bulk. The band gap decreases with Au content increasing from 3 vol% to 37 vol % but increases as Au content further increases.展开更多
After compositing with SiO_2 layers, it is shown that superlattice-like Sb/SiO_2 thin films have higher crystallization temperature（~240°C）, larger crystallization activation energy（6.22 e V）, and better data...After compositing with SiO_2 layers, it is shown that superlattice-like Sb/SiO_2 thin films have higher crystallization temperature（~240°C）, larger crystallization activation energy（6.22 e V）, and better data retention ability（189°C for 10 y）. The crystallization of Sb in superlattice-like Sb/SiO_2 thin films is restrained by the multilayer interfaces. The reversible resistance transition can be achieved by an electric pulse as short as 8 ns for the Sb（3 nm）/SiO_2（7 nm）-based phase change memory cell. A lower operation power consumption of 0.09 m W and a good endurance of 3.0 × 10~6 cycles are achieved. In addition, the superlattice-like Sb（3 nm）/SiO_2（7 nm） thin film shows a low thermal conductivity of 0.13 W/（m·K）.展开更多
The uniform transparent TiO2/SiO2 photocatalytic composite thin films are prepared by sol-gel method on the soda lime glass substrates, and characterized by UV-visible spectroscopy, X-ray diffraction (XRD), transmissi...The uniform transparent TiO2/SiO2 photocatalytic composite thin films are prepared by sol-gel method on the soda lime glass substrates, and characterized by UV-visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), BET surface area, FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that the addition of SiO2 to TiO2 thin films can suppress the grain growth of TiO2 crystal, increase the hydroxyl content on the surface of TiO2 films, lower the contact angle for water on TiO, films and enhance the hydrophilic property of TiO2 films. The super-hydrophilic TiO2/SiO2 photocatalytic composite thin films with the contact angle of 0((o) under bar) are obtained by the addition of 10%-20% SiO2 in mole fraction.展开更多
By means of scanning electron microscope(SEM)and high voltage electron microscope(HVEM)we have observed and analysed morphology and micro-structure of silicon oxide film with different thickness formed on(111)silicon ...By means of scanning electron microscope(SEM)and high voltage electron microscope(HVEM)we have observed and analysed morphology and micro-structure of silicon oxide film with different thickness formed on(111)silicon monocrystal under dry oxygen atmosphere at 1100℃.Compared with their oxidation kinetic curves consisted of three stages,we suggested a mechanism on forming silicon oxide film.According to electron and X-ray diffraction analyses the silicon oxide films consisted of silica with different crystal structure.We also have discussed a stacking fault and a dislocation formed in the Si-Sio_2 interface region simulaneously forming silicon oxide film.展开更多
VISIBLE photoluminescence (PL) from nanostructured group Ⅳ semiconductors has attractedgreat attention, since visible PL at room temperature(RT) from porous silicon was discoveredby Canham in 1990. This makes it poss...VISIBLE photoluminescence (PL) from nanostructured group Ⅳ semiconductors has attractedgreat attention, since visible PL at room temperature(RT) from porous silicon was discoveredby Canham in 1990. This makes it possible that the conventional planar technology of sili-con may be used in optoelectronics devices directly. Moreover, it is also an ideal object展开更多
Direct integration of lithium-ion battery （LIB） with electronic devices on the same Si substrate can significantly miniaturize autonomous micro systems. For achieving direct integration, a barrier layer is essential...Direct integration of lithium-ion battery （LIB） with electronic devices on the same Si substrate can significantly miniaturize autonomous micro systems. For achieving direct integration, a barrier layer is essential to be inserted between LIB and the substrate for blocking Li^＋ diffusion. In this paper, the feasibility of thermal SiOa film as the barrier layer is investigated by electrochemical characterization and X-ray photoelectron spectroscopy （XPS）. Due to the negligible side reactions of thermal SiO2 with electrolyte, the solid electrolyte interphase （SEI） layer formed on the surface of the barrier layer is thin and the SEI content mainly consists of hydrocarbon together with slight polyethylene oxide （PEO）, LixPOyFz, and Li2CO3. Although 8-nm thermal SiO2 effectively prevents the substrate from alloying with Li^＋, the whole film changes to Li silicate after electrochemical cycling due to the irreversible chemical reactions of SiO2 with electrolyte. This degrades the performance of the barrier layer against the electrolyte penetration, thus leading to the existence of Li^＋ （in the form of F-Si-Li） and solvent decompositions （with the products of hydrocarbon and PEO） near the barrier layer/substrate interface. Moreover, it is found that the reaction kinetics of thermal SiO2 with electrolyte decrease significantly with increasing the SiO2 thickness and no reactions are found in the bulk of the 30-nm SiO2 film. Therefore, thermal SiO2 with an appropriate thickness is a promising barrier layer for direct integration.展开更多
The composite films of GaSb nanoparticles embedded in SiO2 matrices were fabricated by radio-frequency magnetron co-sputtering. Transmission electron microscope and X-ray diffraction pattern indicate that the GaSb nan...The composite films of GaSb nanoparticles embedded in SiO2 matrices were fabricated by radio-frequency magnetron co-sputtering. Transmission electron microscope and X-ray diffraction pattern indicate that the GaSb nanoparticles were uniformly dispersed in SiO2 matrices. Room temperature transmission spectra exhibit a blue shift of about 2.73 eV. The blue shift increases with decreasing size of GaSb nanoparticles, suggesting the existence of quantum size effects. Room temperature Raman spectra show that there is a larger Raman peak red shift and broadening of the composite films than that of bulk GaSb. This phenomenon is explained by photon confinement effect and tensile stress effect.展开更多
Nanosecond single- and multiple-pulse laser damage studies on HfOffSiO2 high-reflection （HR） coatings are performed at 532 nm. For single-pulse irradiation, the damage is attributed to the defects and the electric i...Nanosecond single- and multiple-pulse laser damage studies on HfOffSiO2 high-reflection （HR） coatings are performed at 532 nm. For single-pulse irradiation, the damage is attributed to the defects and the electric intensity distribution in the multilayer thin films. When the defect density in the irradiated area is high, delami- nation is observed. Other than the 1064 nm laser damage, the plasma scalding of the 532 nm laser damage is not pits-centered for normal incidence, and the size of the plasma scalding has no relation to the defect density and position, but increases with the laser fluence. For multiple-pulse irradiations, some damage sites show deeper precursors than those from the single-shot irradiation due to the accumulation effects. The cumulative laser- induced damages behave as pits without the presence of plasma scalding, which is unaffected by the laser fluence and shot numbers. The damage morphologies and depth information both confirm the fatigue effect of a HfO2/SiO2 HR coating under 532 nm laser irradiation.展开更多
In order to obtain higher light output power, the flip-chip structure is used. We studied the ratio of the light of GaN sides before and after fabricating metal reflector on p-GaN. The SiO2/SiNx dielectric film reflec...In order to obtain higher light output power, the flip-chip structure is used. We studied the ratio of the light of GaN sides before and after fabricating metal reflector on p-GaN. The SiO2/SiNx dielectric film reflectors were deposited through plasma enhance chemical vapor deposition following the fabrication of metal reflector, and then the dielectric film reflectors on the electrodes were etched in order to expose the electrodes to the air. It is found that comparing with the flip-chip GaN-LED without dielectric film reflectors, light output power can be increased by as high as 10.2% after the deposition of 2 pairs of SiO2/SiNx dielectric film reflectors on GaN-LEDs, which cover the sidewalls and the areas without the metal reflector. This result indicates that the high reflector formed by multi-layer dielectric films is useful to enhance the light output power of GaN-based LED, which reflects light from step sidewalls and p-GaN without metal reflector to internal, and then light emits from the surface.展开更多
Positron annihilation lifetime and Doppler broadening of annihilation line techniques have been used to obtain information about the small pore structure and size of porous SiO2 thin film produced by sputtered Al-Si t...Positron annihilation lifetime and Doppler broadening of annihilation line techniques have been used to obtain information about the small pore structure and size of porous SiO2 thin film produced by sputtered Al-Si thin film and etched Al-Si thin film. The film is prepared by an Al/Si 75：25 at.-% （A175Si25） target with the radiofrequency （RF） power of 66 W at room temperature. A 5 wt.-% phosphoric acid solution is used to etch the Al cylinders. All the A1 cylinders dissolved in the solution after 15 h at room temperature, and the sample is subsequently rinsed in pure water. In this way, the porous SiO2 on the Si substrate is produced. From our results, the values of all lifetime components in the spectra of Al-Si thin film are less than 1 ns, but the value of one of the lifetime components in the spectra of porous SiO2 thin film is τ = 7.80 ns. With these values of lifetime, RTE （Rectangular Pore Extension） model has been used to analyze the pore size.展开更多
文摘Microwave electron cyclotron resonance plasma enhanced chemical vapor depositionwas used to grow silicon dioxide films on crystalline silicon substrate for planar optical waveguides.The relationship between plasma parameters and deposition rates was investigated, and the influ-ence of radio frequency substrate bias on properties of SiO2 films was also preliminarily studied.X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, scanning electron mi-croscopy, atomic force microscopy and elllipsometry were used to characterize the deposited films,showing that SiO2 films with good structural and optical properties prepared at low temperaturehave been achieved. They can basically meet the requirements of integrated optical waveguides.
基金Funded by the Innovative Program of Shanghai Municipal Education Commission (No.08YZ97)the National Natural Science Foundation of China (No.10704048)
文摘Fe2O3/SiO2 nano-composite films were prepared by sol-gel technique combining heat treatment in the range of 100-900 ℃. The particle size was observed by FE-SEM. Optical properties of the films were investigated by UV-visible spectra. Structural and magnetic characteristics were investigated through FT-IR and VSM. The transparency of the Fe2O3/SiO2 nano-composite films decreased with the content of the Fe2O3. Water and organic solvent in the films were evaporated with heat treatment, so the transparency of the films was enhanced under high temperature. It is also found that the saturation magnetization （Ms） of the films increases with the temperature. As the content of the Fe2O3 increases, when the content of the Fe2O3 is around 30wt%, the Ms of the films has a maximum value.
基金Project(10574085) supported by the National Natural Science Foundation of ChinaProject(207020) supported by the Science Technology Key Project of the Ministry of Education, China
文摘[SiO2/FePt]5/Ag thin films were deposited by RF magnetron sputtering on the glass substrates and post annealing at 550 ℃ for 30 min in vacuum. Vibrating sample magnetometer and X-ray diffraction analyser were applied to study the magnetic properties and microstructures of the films. The results show that without Ag underlayer [SiO2/FePt]5 films deposited onto the glass are FCC disordered; with the addition of Ag underlayer [SiO]FePt]5/Ag films are changed into L10 and （111） mixed texture. The variation of the SiO2 nonmagnetic layer thickness in [SiO2/FePt]5/Ag films indicates that SiO2-doping plays an important role in improving the order parameter and the perpendicular magnetic anisotropy, and reducing the grain size and intergrain interactions. By controlling SiO2 thickness the highly perpendicular magnetic anisotropy can be obtained in the [SiO2 （0.6 nm）/FePt （3 nm）]5/Ag （50 nm） films and highly （001）-oriented films can be obtained in the [SiO2 （2 nm）/FePt （3 nm）]5/Ag （50 nm） films.
文摘Total dose effects and single event effects on radiation-hardened power vertical double-diffusion metal oxide semiconductor（VDMOS） devices with composite SiO2-Si3N4 film gates are investigated.The relationships among the important electrical parameters of the samples with different thickness SiO2-Si3N4 films,such as threshold voltage,breakdown voltage,and on-state resistance in accumulated dose,are discussed.The total dose experiment results show that the breakdown voltage and the on-state resistance barely change with the accumulated dose.However,the relationships between the threshold voltages of the samples and the accumulated dose are more complex,and not only positively drift,but also negatively drift.At the end of the total dose experiment,we select the group of samples which have the smaller threshold voltage shift to carry out the single event effect studies.We find that the samples with appropriate thickness ratio SiO2-Si3N4 films have a good radiation-hardening ability.This method may be useful in solving both the SEGR and the total dose problems with the composite SiO2-Si3N4 films.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 50842028 and 50972012)the National Basic Research Program of China (Grant No 2007CB613301)
文摘Nano metal-particle dispersed glasses are the attractive candidates for nonlinear optical material applications. Au/SiO2 nano-composite thin films with 3 vol% to 65 vol% Au are prepared by inductively coupled plasma sputtering. Au particles as perfect spheres with diameters between 10 nm and 30 nm are uniformly dispersed in the SiO2 matrix. Optical absorption peaks due to the surface plasmon resonance of Au particles are observed. The absorption property is enhanced with the increase of Au content, showing a maximum value in the films with 37 vol% Au. The absorption curves of the Au/SiO2 thin films with 3 vol% to 37 vol% Au accord well with the theoretical optical absorption spectra obtained from Mie resonance theory. Increasing Au content over 37 vol% results in the partial connection of Au particles, whereby the intensity of the absorption peak is weakened and ultimately replaced by the optical absorption of the bulk. The band gap decreases with Au content increasing from 3 vol% to 37 vol % but increases as Au content further increases.
基金Supported by the National Natural Science Foundation of China under Grant No 11774438the Natural Science Foundation of Jiangsu Province under Grant No BK20151172+2 种基金the Changzhou Science and Technology Bureau under Grant No CJ20160028the Qing Lan Project,the Opening Project of State Key Laboratory of Silicon Materials under Grant No SKL2017-04the Opening Project of Key Laboratory of Microelectronic Devices and Integrated Technology of Institute of Microelectronics of Chinese Academy of Sciences
文摘After compositing with SiO_2 layers, it is shown that superlattice-like Sb/SiO_2 thin films have higher crystallization temperature（~240°C）, larger crystallization activation energy（6.22 e V）, and better data retention ability（189°C for 10 y）. The crystallization of Sb in superlattice-like Sb/SiO_2 thin films is restrained by the multilayer interfaces. The reversible resistance transition can be achieved by an electric pulse as short as 8 ns for the Sb（3 nm）/SiO_2（7 nm）-based phase change memory cell. A lower operation power consumption of 0.09 m W and a good endurance of 3.0 × 10~6 cycles are achieved. In addition, the superlattice-like Sb（3 nm）/SiO_2（7 nm） thin film shows a low thermal conductivity of 0.13 W/（m·K）.
基金This work was financially supported by the Foundation for University Key Teachers by the Ministry of Education, theKey Resear
文摘The uniform transparent TiO2/SiO2 photocatalytic composite thin films are prepared by sol-gel method on the soda lime glass substrates, and characterized by UV-visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), BET surface area, FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that the addition of SiO2 to TiO2 thin films can suppress the grain growth of TiO2 crystal, increase the hydroxyl content on the surface of TiO2 films, lower the contact angle for water on TiO, films and enhance the hydrophilic property of TiO2 films. The super-hydrophilic TiO2/SiO2 photocatalytic composite thin films with the contact angle of 0((o) under bar) are obtained by the addition of 10%-20% SiO2 in mole fraction.
文摘By means of scanning electron microscope(SEM)and high voltage electron microscope(HVEM)we have observed and analysed morphology and micro-structure of silicon oxide film with different thickness formed on(111)silicon monocrystal under dry oxygen atmosphere at 1100℃.Compared with their oxidation kinetic curves consisted of three stages,we suggested a mechanism on forming silicon oxide film.According to electron and X-ray diffraction analyses the silicon oxide films consisted of silica with different crystal structure.We also have discussed a stacking fault and a dislocation formed in the Si-Sio_2 interface region simulaneously forming silicon oxide film.
文摘VISIBLE photoluminescence (PL) from nanostructured group Ⅳ semiconductors has attractedgreat attention, since visible PL at room temperature(RT) from porous silicon was discoveredby Canham in 1990. This makes it possible that the conventional planar technology of sili-con may be used in optoelectronics devices directly. Moreover, it is also an ideal object
基金This work was supported by the Natural Science Foundation of Jiangsu Province （Grant No. BK20140639） and the National Natural Science Foundation of China （Grant No. 21206070）.
文摘Direct integration of lithium-ion battery （LIB） with electronic devices on the same Si substrate can significantly miniaturize autonomous micro systems. For achieving direct integration, a barrier layer is essential to be inserted between LIB and the substrate for blocking Li^＋ diffusion. In this paper, the feasibility of thermal SiOa film as the barrier layer is investigated by electrochemical characterization and X-ray photoelectron spectroscopy （XPS）. Due to the negligible side reactions of thermal SiO2 with electrolyte, the solid electrolyte interphase （SEI） layer formed on the surface of the barrier layer is thin and the SEI content mainly consists of hydrocarbon together with slight polyethylene oxide （PEO）, LixPOyFz, and Li2CO3. Although 8-nm thermal SiO2 effectively prevents the substrate from alloying with Li^＋, the whole film changes to Li silicate after electrochemical cycling due to the irreversible chemical reactions of SiO2 with electrolyte. This degrades the performance of the barrier layer against the electrolyte penetration, thus leading to the existence of Li^＋ （in the form of F-Si-Li） and solvent decompositions （with the products of hydrocarbon and PEO） near the barrier layer/substrate interface. Moreover, it is found that the reaction kinetics of thermal SiO2 with electrolyte decrease significantly with increasing the SiO2 thickness and no reactions are found in the bulk of the 30-nm SiO2 film. Therefore, thermal SiO2 with an appropriate thickness is a promising barrier layer for direct integration.
基金the Chinese Climbing Program. We would like to thank Profs. Xu Cunyi and Zuo Jian for Raman measurements at the Center of Structure and Element Analysis (USTC) .
文摘The composite films of GaSb nanoparticles embedded in SiO2 matrices were fabricated by radio-frequency magnetron co-sputtering. Transmission electron microscope and X-ray diffraction pattern indicate that the GaSb nanoparticles were uniformly dispersed in SiO2 matrices. Room temperature transmission spectra exhibit a blue shift of about 2.73 eV. The blue shift increases with decreasing size of GaSb nanoparticles, suggesting the existence of quantum size effects. Room temperature Raman spectra show that there is a larger Raman peak red shift and broadening of the composite films than that of bulk GaSb. This phenomenon is explained by photon confinement effect and tensile stress effect.
基金supported by the National Natural Science Foundation of China under Grant Nos.11104293and 61308021
文摘Nanosecond single- and multiple-pulse laser damage studies on HfOffSiO2 high-reflection （HR） coatings are performed at 532 nm. For single-pulse irradiation, the damage is attributed to the defects and the electric intensity distribution in the multilayer thin films. When the defect density in the irradiated area is high, delami- nation is observed. Other than the 1064 nm laser damage, the plasma scalding of the 532 nm laser damage is not pits-centered for normal incidence, and the size of the plasma scalding has no relation to the defect density and position, but increases with the laser fluence. For multiple-pulse irradiations, some damage sites show deeper precursors than those from the single-shot irradiation due to the accumulation effects. The cumulative laser- induced damages behave as pits without the presence of plasma scalding, which is unaffected by the laser fluence and shot numbers. The damage morphologies and depth information both confirm the fatigue effect of a HfO2/SiO2 HR coating under 532 nm laser irradiation.
基金Supported by the National Basic Research Program of China (Grant No. 2006CB604902)the Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality (Grant No. 05002015200504)
文摘In order to obtain higher light output power, the flip-chip structure is used. We studied the ratio of the light of GaN sides before and after fabricating metal reflector on p-GaN. The SiO2/SiNx dielectric film reflectors were deposited through plasma enhance chemical vapor deposition following the fabrication of metal reflector, and then the dielectric film reflectors on the electrodes were etched in order to expose the electrodes to the air. It is found that comparing with the flip-chip GaN-LED without dielectric film reflectors, light output power can be increased by as high as 10.2% after the deposition of 2 pairs of SiO2/SiNx dielectric film reflectors on GaN-LEDs, which cover the sidewalls and the areas without the metal reflector. This result indicates that the high reflector formed by multi-layer dielectric films is useful to enhance the light output power of GaN-based LED, which reflects light from step sidewalls and p-GaN without metal reflector to internal, and then light emits from the surface.
基金Supported by National Natural Science Foundation of China (10575112, 60606011)
文摘Positron annihilation lifetime and Doppler broadening of annihilation line techniques have been used to obtain information about the small pore structure and size of porous SiO2 thin film produced by sputtered Al-Si thin film and etched Al-Si thin film. The film is prepared by an Al/Si 75：25 at.-% （A175Si25） target with the radiofrequency （RF） power of 66 W at room temperature. A 5 wt.-% phosphoric acid solution is used to etch the Al cylinders. All the A1 cylinders dissolved in the solution after 15 h at room temperature, and the sample is subsequently rinsed in pure water. In this way, the porous SiO2 on the Si substrate is produced. From our results, the values of all lifetime components in the spectra of Al-Si thin film are less than 1 ns, but the value of one of the lifetime components in the spectra of porous SiO2 thin film is τ = 7.80 ns. With these values of lifetime, RTE （Rectangular Pore Extension） model has been used to analyze the pore size.
