Performance modulation of ZnO optoelectronic devices in the presence of proper piezoelectric polarization charges has been widely reported, whereas relatively less work has been performed about the influence of photoe...Performance modulation of ZnO optoelectronic devices in the presence of proper piezoelectric polarization charges has been widely reported, whereas relatively less work has been performed about the influence of photoexcitation on piezotronics. In this stud~ we experimentally investigated the performance evolution of ZnO piezotronic strain sensor under various 365 nm UV irradiation densities. The device demonstrated a response ratio of -200 under no illumination and under -0.53% compressive strain, and the response time is approximately 0.3 s. However, tremendous performance degradation was observed with the increase in the illumination densi~, which is attributed to the W-modulated change in the free electron concentration and Schottky barrier height. It was observed that increased carrier density intensifies the screening effect and thus, the modulation ability of piezo-polarization charges weakens. Meanwhile, the deterioration of rectifying behavior at the interface under UV illumination also jeopardizes the device performance.展开更多
A dielectric barrier discharge (DBD) reactor consisting of water-filled dielectric tube electrodes was used for the treatment of wastewater. The inner dielectric tube, which acted as the discharging electrode, was fil...A dielectric barrier discharge (DBD) reactor consisting of water-filled dielectric tube electrodes was used for the treatment of wastewater. The inner dielectric tube, which acted as the discharging electrode, was filled with an aqueous electrolyte solution. The outer dielectric tube, which served as the other electrode, was in contact with the wastewater, which was grounded. The present reactor system was energy-efficient for the production of ozone, not only because the perfect contact between the aqueous electrode and the dielectric surface minimized the loss of the electrical energy, but also because the DBD reactor was cooled by the wastewater. In addition, the ultraviolet (UV) light produced in the DBD reactor was able to assist in the wastewater treatment since the quartz tube used as the dielectric material was UV-transparent. The performance of the present DBD system was evaluated using a synthetic wastewater formed from distilled water and an azo dye, amaranth. The experimental parameters were the concentration of the electrolyte in the aqueous electrode, the discharge power, the initial pH of the wastewater and the concentration of hydrogen peroxide added to the wastewater. The wastewater treatment system was found to be effective for achieving decomposition of the dye.展开更多
This paper presents both results of a numerical modeling and an experimental study of the influence of various parameters on the radiation characteristics of barrier discharge lamp working in He/D2O mixture.It is obta...This paper presents both results of a numerical modeling and an experimental study of the influence of various parameters on the radiation characteristics of barrier discharge lamp working in He/D2O mixture.It is obtained that the intensity of ultraviolet radiation is a non-monotonic function of both the water and the helium pressures.The experimental results also show that the increase of both the discharge voltage and the discharge pulse frequency leads to the increase of radiation intensity.The comparison between the experimentally obtained data and the results of numerical modeling allows us to define the mechanism controlling the ultraviolet radiation in He/D2O mixture at various parameters.展开更多
The physicochemical processes of dielectric barrier discharge （DBD） such as insitu formation of chemically active species and emission of ultraviolet （UV）/visible light were utilized for the treatment of a simulat...The physicochemical processes of dielectric barrier discharge （DBD） such as insitu formation of chemically active species and emission of ultraviolet （UV）/visible light were utilized for the treatment of a simulated wastewater formed with Acid Red 4 as the model organic contaminant. The chemically active species （mostly ozone） produced in the DBD reactor were well distributed in the wastewater using a porous gas diffuser, thereby increasing the gas-liquid contact area. For the purpose of making the best use of the light emission, a titanium oxide-based photocatalyst was incorporated in the wastewater treating system. The experimental parameters chosen were the voltage applied to the DBD reactor, the initial pH of the wastewater, and the concentration of hydrogen peroxide added to the wastewater. The results have clearly shown that the present system capable of degrading organic contaminants in two ways （photocatalysis and ozonation） may be a promising wastewater treatment technology.展开更多
An AIGaN-based back-illuminated ultraviolet p-i-n detector is designed and its performance is analysed both simulately and experimentally. The width of p- and i-regions has been optimized to the best theoretic values....An AIGaN-based back-illuminated ultraviolet p-i-n detector is designed and its performance is analysed both simulately and experimentally. The width of p- and i-regions has been optimized to the best theoretic values. It is indicated that the changing of responsivity with increase of bias can not be attributed to the expansion of depletion layer as it is believed, but to two reasons： 1） the effect of GaN/AlGaN heterojunction barrier to block the electrons decreases with higher bias and 2） the recombination rate of excess carriers decreases due to the building up of an electric field in depletion region. At zero bias, the simulated responsivity reaches its maximum of 0.12 A/W with quantum efficiency of 55.1%. The measured peak responsivity is more than 0.09 A/W with quantum efficiency greater than 41.6%. The experimental data are almost consistent with the results of the simulation.展开更多
A negative unipolar pulsed voltage is applied to study internal electrical parameters of the xenon filled dielectric barrier discharge （DBD） sources. The VUV radiation emitted from these sources is characterized by ...A negative unipolar pulsed voltage is applied to study internal electrical parameters of the xenon filled dielectric barrier discharge （DBD） sources. The VUV radiation emitted from these sources is characterized by means of the photoluminescence intensity of the red phosphor pellet. The red phosphor converts the VUV radiation into visible radiation and the emission spectra include a peak at 619.56 nm. The emission characteristics of the red phosphor are analyzed in terms of the pressure-distance （pd）, rise time and frequency of the pulsed voltage waveform. The emission intensity measured at different operational conditions confirms that the formation and decay of the xenon excimer, Xe2^＊, increase with the increase in reduced electric field, E/N. After exceeding certain limits of E/N, the intensity of Xe2^＊ decreases rapidly.展开更多
A combined plasma photolysis （CPP） reactor that utilized the dielectric barrier discharge （DBD） plasma together with DBD-driven KrI^＊ excimer ultraviolet emission was applied to the decomposition of H2S gas. The ...A combined plasma photolysis （CPP） reactor that utilized the dielectric barrier discharge （DBD） plasma together with DBD-driven KrI^＊ excimer ultraviolet emission was applied to the decomposition of H2S gas. The effects of applied voltage, input current, gas flow velocity, original concentration as well as the ratio of Kr/I2 mixture on H2S removal efficiency were investigated. Gas streams containing H2S were separately treated with single DBD and CPP reactor under the same conditions. In comparison to DBD, CPP could greatly enhance the H2S removal efficiency at the same applied voltage, inlet gas concentration and gas flow velocity. In addition, the reaction mechanism was also discussed in this paper.展开更多
基金This work was supported by the National Basic Research Program of China （No. 2013CB932602）, the Program of Introducing Talents of Discipline to Universities （No. B14003）, National Natural Science Foundation of China （Nos. 51527802 and 51232001）, Beijing Municipal Science ＆ Technology Commission, and the Fundamental Research Funds for Central Universities.
文摘Performance modulation of ZnO optoelectronic devices in the presence of proper piezoelectric polarization charges has been widely reported, whereas relatively less work has been performed about the influence of photoexcitation on piezotronics. In this stud~ we experimentally investigated the performance evolution of ZnO piezotronic strain sensor under various 365 nm UV irradiation densities. The device demonstrated a response ratio of -200 under no illumination and under -0.53% compressive strain, and the response time is approximately 0.3 s. However, tremendous performance degradation was observed with the increase in the illumination densi~, which is attributed to the W-modulated change in the free electron concentration and Schottky barrier height. It was observed that increased carrier density intensifies the screening effect and thus, the modulation ability of piezo-polarization charges weakens. Meanwhile, the deterioration of rectifying behavior at the interface under UV illumination also jeopardizes the device performance.
文摘A dielectric barrier discharge (DBD) reactor consisting of water-filled dielectric tube electrodes was used for the treatment of wastewater. The inner dielectric tube, which acted as the discharging electrode, was filled with an aqueous electrolyte solution. The outer dielectric tube, which served as the other electrode, was in contact with the wastewater, which was grounded. The present reactor system was energy-efficient for the production of ozone, not only because the perfect contact between the aqueous electrode and the dielectric surface minimized the loss of the electrical energy, but also because the DBD reactor was cooled by the wastewater. In addition, the ultraviolet (UV) light produced in the DBD reactor was able to assist in the wastewater treatment since the quartz tube used as the dielectric material was UV-transparent. The performance of the present DBD system was evaluated using a synthetic wastewater formed from distilled water and an azo dye, amaranth. The experimental parameters were the concentration of the electrolyte in the aqueous electrode, the discharge power, the initial pH of the wastewater and the concentration of hydrogen peroxide added to the wastewater. The wastewater treatment system was found to be effective for achieving decomposition of the dye.
文摘This paper presents both results of a numerical modeling and an experimental study of the influence of various parameters on the radiation characteristics of barrier discharge lamp working in He/D2O mixture.It is obtained that the intensity of ultraviolet radiation is a non-monotonic function of both the water and the helium pressures.The experimental results also show that the increase of both the discharge voltage and the discharge pulse frequency leads to the increase of radiation intensity.The comparison between the experimentally obtained data and the results of numerical modeling allows us to define the mechanism controlling the ultraviolet radiation in He/D2O mixture at various parameters.
文摘The physicochemical processes of dielectric barrier discharge （DBD） such as insitu formation of chemically active species and emission of ultraviolet （UV）/visible light were utilized for the treatment of a simulated wastewater formed with Acid Red 4 as the model organic contaminant. The chemically active species （mostly ozone） produced in the DBD reactor were well distributed in the wastewater using a porous gas diffuser, thereby increasing the gas-liquid contact area. For the purpose of making the best use of the light emission, a titanium oxide-based photocatalyst was incorporated in the wastewater treating system. The experimental parameters chosen were the voltage applied to the DBD reactor, the initial pH of the wastewater, and the concentration of hydrogen peroxide added to the wastewater. The results have clearly shown that the present system capable of degrading organic contaminants in two ways （photocatalysis and ozonation） may be a promising wastewater treatment technology.
文摘An AIGaN-based back-illuminated ultraviolet p-i-n detector is designed and its performance is analysed both simulately and experimentally. The width of p- and i-regions has been optimized to the best theoretic values. It is indicated that the changing of responsivity with increase of bias can not be attributed to the expansion of depletion layer as it is believed, but to two reasons： 1） the effect of GaN/AlGaN heterojunction barrier to block the electrons decreases with higher bias and 2） the recombination rate of excess carriers decreases due to the building up of an electric field in depletion region. At zero bias, the simulated responsivity reaches its maximum of 0.12 A/W with quantum efficiency of 55.1%. The measured peak responsivity is more than 0.09 A/W with quantum efficiency greater than 41.6%. The experimental data are almost consistent with the results of the simulation.
文摘A negative unipolar pulsed voltage is applied to study internal electrical parameters of the xenon filled dielectric barrier discharge （DBD） sources. The VUV radiation emitted from these sources is characterized by means of the photoluminescence intensity of the red phosphor pellet. The red phosphor converts the VUV radiation into visible radiation and the emission spectra include a peak at 619.56 nm. The emission characteristics of the red phosphor are analyzed in terms of the pressure-distance （pd）, rise time and frequency of the pulsed voltage waveform. The emission intensity measured at different operational conditions confirms that the formation and decay of the xenon excimer, Xe2^＊, increase with the increase in reduced electric field, E/N. After exceeding certain limits of E/N, the intensity of Xe2^＊ decreases rapidly.
基金supported by Natural Science Foundation of Shanghai (No.07ZR14004)
文摘A combined plasma photolysis （CPP） reactor that utilized the dielectric barrier discharge （DBD） plasma together with DBD-driven KrI^＊ excimer ultraviolet emission was applied to the decomposition of H2S gas. The effects of applied voltage, input current, gas flow velocity, original concentration as well as the ratio of Kr/I2 mixture on H2S removal efficiency were investigated. Gas streams containing H2S were separately treated with single DBD and CPP reactor under the same conditions. In comparison to DBD, CPP could greatly enhance the H2S removal efficiency at the same applied voltage, inlet gas concentration and gas flow velocity. In addition, the reaction mechanism was also discussed in this paper.
