Doping can improve the band alignment at the metal-semiconductor interface to modify the corresponding Schottky barrier,which is crucial for the realization of high-performance logic components.Here,we systematically ...Doping can improve the band alignment at the metal-semiconductor interface to modify the corresponding Schottky barrier,which is crucial for the realization of high-performance logic components.Here,we systematically investigated a convenient and effective method,ultraviolet ozone treatment,for p-type doping of MoTe2 field-effect transistors to enormously enhance the corresponding electrical performance.The resulted hole concentration and mobility are near 100 times enhanced to be〜1.0×10^13 cm^-2 and 101.4 cm^2/(V·s),respectively,and the conductivity is improved by 5 orders of magnitude.These values are comparable to the highest ones ever obtained via annealing doping or non-lithographic fabrication methods at room temperature.Compared with the pristine one,the photoresponsivity(522 mA/W)is enhanced approximately 100 times.Such excellent performances can be attributed to the sharply reduced Schottky barrier because of the surface charge transfer from MoTe2 to MoOx(x<3),as proved by photoemission spectroscopy.Additionally,the p-doped devices exhibit excellent stability in ambient air.Our findings show significant potential in future nanoelectronic and optoelectronic applications.展开更多
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
研制一种以薄的高阻Al Ga N覆盖层作为肖特基势垒增强层的N-Al Ga N基金属-半导体-金属(MSM)日盲紫外光电探测器。与无覆盖层的参考器件相比,覆盖高阻Al Ga N层后探测器的暗电流大幅度减小。在5 V偏压下,覆盖高阻Al Ga N层的光电探测器...研制一种以薄的高阻Al Ga N覆盖层作为肖特基势垒增强层的N-Al Ga N基金属-半导体-金属(MSM)日盲紫外光电探测器。与无覆盖层的参考器件相比,覆盖高阻Al Ga N层后探测器的暗电流大幅度减小。在5 V偏压下,覆盖高阻Al Ga N层的光电探测器的暗电流为1.6 p A,响应度为22.5 m A/W,日盲紫外抑制比大于103,探测率为6.3×1010cm·Hz1/2/W。展开更多
目的探讨紫草乳膏外用联合窄谱中波紫外线(narrow band ultraviolet,NB-UVB)照射对寻常型银屑病患者皮肤屏障及免疫功能的影响。方法将符合入选标准的100例寻常型银屑病患者按随机数字表法分为2组,每组50例。对照组给予NB-UVB全身照射,...目的探讨紫草乳膏外用联合窄谱中波紫外线(narrow band ultraviolet,NB-UVB)照射对寻常型银屑病患者皮肤屏障及免疫功能的影响。方法将符合入选标准的100例寻常型银屑病患者按随机数字表法分为2组,每组50例。对照组给予NB-UVB全身照射,观察组在对照组基础上于皮损部位涂擦紫草软膏。2组均治疗4周。分别于治疗前后进行皮损面积和严重程度指数(psoriasis area and severity index,PASI)评分,采用VAS量表评估皮肤瘙痒程度;采用DermaLab皮肤无创检测系统检测皮脂含量、角质层含水量、经表皮失水量(transepidennal water loss,TEWL),采用流式细胞仪检测患者外周血T淋巴细胞亚群(CD4^+、CD8^+、CD4^+/CD8^+)水平,评价临床疗效。结果观察组总有效率为98.0%(49/50)、对照组为84.0%(42/50),2组比较差异有统计学意义(χ^2=5.980,P=0.014)。观察组治疗后2、4周PASI评分与瘙痒评分均低于对照组(t值分别为3.462、2.833,P<0.01)。治疗后,观察组角质层含水量[(54.34±5.04)%比(49.03±5.26)%,t=5.154]、CD4^+[(42.06±4.68)%比(33.01±3.07)%,t=11.433]水平高于对照组(P<0.01),TEWL[(15.87±4.22)g/(h•m^2)比(19.87±3.06)g/(h•m^2),t=5.426]、皮脂含量[(143.03±11.60)μg/cm^2比(130.79±14.54)μg/cm^2,t=4.653]、CD8^+[(20.89±3.44)%比(26.03±3.44)%,t=7.471]水平、CD4^+/CD8^+[(1.89±0.29)比(1.43±0.27),t=8.209]比值均低于对照组(P<0.01)。结论紫草乳膏外用联合NB-UVB照射可有效改善寻常型银屑病患者的临床症状、提高皮肤屏障功能与免疫功能。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
基金We acknowledge the financial support from the National Natural Science Foundation of China(Nos.11874427,11874423).Dr.H an H uang acknowledges support from the Innovation-Driven project of Central South University(No.2017CX018)and from the Natural Science Foundation of H unan province(No.2016JJ1021).Mr.Xiaoming Zheng acknowledges the support from the Fundamental Research Funds for the Central Universities of Central South University(No.2017zzts066).
文摘Doping can improve the band alignment at the metal-semiconductor interface to modify the corresponding Schottky barrier,which is crucial for the realization of high-performance logic components.Here,we systematically investigated a convenient and effective method,ultraviolet ozone treatment,for p-type doping of MoTe2 field-effect transistors to enormously enhance the corresponding electrical performance.The resulted hole concentration and mobility are near 100 times enhanced to be〜1.0×10^13 cm^-2 and 101.4 cm^2/(V·s),respectively,and the conductivity is improved by 5 orders of magnitude.These values are comparable to the highest ones ever obtained via annealing doping or non-lithographic fabrication methods at room temperature.Compared with the pristine one,the photoresponsivity(522 mA/W)is enhanced approximately 100 times.Such excellent performances can be attributed to the sharply reduced Schottky barrier because of the surface charge transfer from MoTe2 to MoOx(x<3),as proved by photoemission spectroscopy.Additionally,the p-doped devices exhibit excellent stability in ambient air.Our findings show significant potential in future nanoelectronic and optoelectronic applications.
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.
文摘研制一种以薄的高阻Al Ga N覆盖层作为肖特基势垒增强层的N-Al Ga N基金属-半导体-金属(MSM)日盲紫外光电探测器。与无覆盖层的参考器件相比,覆盖高阻Al Ga N层后探测器的暗电流大幅度减小。在5 V偏压下,覆盖高阻Al Ga N层的光电探测器的暗电流为1.6 p A,响应度为22.5 m A/W,日盲紫外抑制比大于103,探测率为6.3×1010cm·Hz1/2/W。
文摘目的探讨紫草乳膏外用联合窄谱中波紫外线(narrow band ultraviolet,NB-UVB)照射对寻常型银屑病患者皮肤屏障及免疫功能的影响。方法将符合入选标准的100例寻常型银屑病患者按随机数字表法分为2组,每组50例。对照组给予NB-UVB全身照射,观察组在对照组基础上于皮损部位涂擦紫草软膏。2组均治疗4周。分别于治疗前后进行皮损面积和严重程度指数(psoriasis area and severity index,PASI)评分,采用VAS量表评估皮肤瘙痒程度;采用DermaLab皮肤无创检测系统检测皮脂含量、角质层含水量、经表皮失水量(transepidennal water loss,TEWL),采用流式细胞仪检测患者外周血T淋巴细胞亚群(CD4^+、CD8^+、CD4^+/CD8^+)水平,评价临床疗效。结果观察组总有效率为98.0%(49/50)、对照组为84.0%(42/50),2组比较差异有统计学意义(χ^2=5.980,P=0.014)。观察组治疗后2、4周PASI评分与瘙痒评分均低于对照组(t值分别为3.462、2.833,P<0.01)。治疗后,观察组角质层含水量[(54.34±5.04)%比(49.03±5.26)%,t=5.154]、CD4^+[(42.06±4.68)%比(33.01±3.07)%,t=11.433]水平高于对照组(P<0.01),TEWL[(15.87±4.22)g/(h•m^2)比(19.87±3.06)g/(h•m^2),t=5.426]、皮脂含量[(143.03±11.60)μg/cm^2比(130.79±14.54)μg/cm^2,t=4.653]、CD8^+[(20.89±3.44)%比(26.03±3.44)%,t=7.471]水平、CD4^+/CD8^+[(1.89±0.29)比(1.43±0.27),t=8.209]比值均低于对照组(P<0.01)。结论紫草乳膏外用联合NB-UVB照射可有效改善寻常型银屑病患者的临床症状、提高皮肤屏障功能与免疫功能。
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.
