Fast-speed self-powered PEDOT:PSS/α-Ga_(2)O_(3)nanorod array/FTO photodetector with solar-blind UV/visible dual-band photodetection

Theα-Ga2 O_(3)nanorod array is grown on FTO by hydrothermal and annealing processes.And a self-powered PEDOT:PSS/α-Ga_(2)O_(3)nanorod array/FTO(PGF)photodetector has been demonstrated by spin coating PEDOT:PSS on theα-Ga_(2)O_(3)nanorod array.Successfully,the PGF photodetector shows solar-blind UV/visible dual-band photodetection.Our device possesses comparable solar-blind UV responsivity(0.18 mA/W at 235 nm)and much faster response speed(0.102 s)than most of the reported self-poweredα-Ga_(2)O_(3)nanorod array solar-blind UV photodetectors.And it presents the featured and distinguished visible band photoresponse with a response speed of 0.136 s at 540 nm.The response time is also much faster than the other non-self-poweredβ-Ga_(2)O_(3)DUV/visible dual-band photodetectors due to the fast-speed separation of photogenerated carries by the built-in electric field in the depletion regions of PEDOT:PSS/α-Ga_(2)O_(3)heterojunction.The results herein may prove a promising way to realize fast-speed self-poweredα-Ga_(2)O_(3)photodetectors with solar-blind UV/visible dual-band photodetection by simple processes for the applications of multiple-target tracking,imaging,machine vision and communication.

High-speed performance self-powered short wave ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)

High-speed solar-blind short wavelength ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)layers with Pt contacts were demonstrated and their properties were studied in detail.Theκ(ε)-Ga_(2)O_(3)layers were deposited by the halide vapor phase epitaxy on patterned GaN templates with sapphire substrates.The spectral dependencies of the photoelectric properties of struc-tures were analyzed in the wavelength interval 200-370 nm.The maximum photo to dark current ratio,responsivity,detectiv-ity and external quantum efficiency of structures were determined as:180.86 arb.un.,3.57 A/W,1.78×10^(12) Hz^(0.5)∙cm·W^(-1) and 2193.6%,respectively,at a wavelength of 200 nm and an applied voltage of 1 V.The enhancement of the photoresponse was caused by the decrease in the Schottky barrier at the Pt/κ(ε)-Ga_(2)O_(3)interface under ultraviolet exposure.The detectors demon-strated could functionalize in self-powered mode due to built-in electric field at the Pt/κ(ε)-Ga_(2)O_(3)interface.The responsivity and external quantum efficiency of the structures at a wavelength of 254 nm and zero applied voltage were 0.9 mA/W and 0.46%,respectively.The rise and decay times in self-powered mode did not exceed 100 ms.

A theoretical and experimental evaluation of Ⅲ–nitride solar-blind UV photocathode

We have developed a superior solar-blind ultraviolet （UV） photocathode with an AlxGa1_xrN photocathode （x ～ 0.45） in semi-transparent mode, and assessed spectra radiant sensitivity related to practical use. Betbre being grown over a basal plane sapphire substrate by low-pressure metal organic chemical vapor deposition （MOCVD）, a reasonable design was made to the photocathode epitaxy structure, focusing on the AlxGa1_xN： Mg active layer, then followed by a comprehen- sive analysis of the structural and optical characterization. The spectra radiant sensitivity is peaked of 41.395 mA/W at wavelength 257 nm and then decreases by about 3 to 4 decades at 400 nm demonstrating the ability of this photocathode for solar-blind application prospects.

TiO_2 Thin Film UV Detectors Deposited by DC Reactive Magnetron Sputtering

Crystalline TiO2 thin films were prepared by DC reactive magnetron sputtering on indium-tin oxide（ITO） thin film deposited on quartz substrate, the photoconductive UV detector on TiO2 thin films was based on a sandwich structure of C/ TiO2/ITO. The measurement of the I-V characteristics for these devices shows good ohmic contact. The photoresponse of TiO2 thin films was analyzed at different bias voltage. The detector shows a good photoresponse with a rise time of 2 s and a fall time of 40 s, the photocurrent is linearly increased with the bias voltage.

Investigation of Ga_(2)O_(3)/diamond heterostructure solar-blind avalanche photodiode via TCAD simulation

A Ga_(2)O_(3)/diamond separate absorption and multiplication avalanche photodiode(SAM-APD)with mesa structure has been proposed and simulated.The simulation is based on an optimized Ga_(2)O_(3)/diamond heterostructure TCAD physical model,which is revised by repeated comparison with the experimental data from the literature.Since both Ga_(2)O_(3)and diamond are ultra-wide bandgap semiconductor materials,the Ga_(2)O_(3)/diamond SAM-APD shows good solar-blind detection ability,and the corresponding cutoff wavelength is about 263 nm.The doping distribution and the electric field distribution of the SAM-APD are discussed,and the simulation results show that the gain of the designed device can reach 5×10^(4)and the peak responsivity can reach a value as high as 78 A/W.

Flow Injection Analysis of Hydrazine in the Aqueous Streams of Purex Process by Liquid Chromatography System Coupled with UV-Visible Detector

Present study describes the development of a rapid, sensitive and selective flow injection analysis of hydrazine in the aqueous streams of purex process by liquid chromatography system coupled with UV-Visible detector. The method is based on the formation of yellow coloured azine complex by reaction of hydrazine with para-dimethy laminobenzaldehyde (pDMAB). The formed yellow coloured complex is stable in acidic medium and has a maximum absorption at 460 nm. The presence of uranium in hydrazine solution is not interfering in the analysis. Under optimum condition, the absorption intensity linearly increased with the concentration of hydrazine in the range from 0.05-10 mg?L–1 with a correlation coefficient of R2=0.9999 (n=7). The experimental detection limit is 0.05mgL–1. The sampling frequency is 15 samples h–1 and the relative standard deviation was 2.1% for 0.05 mg?L–1. This method is suitable for automatic and continuous analysis and successfully applied to determine the concentration of hydrazine in the aqueous stream of nuclear fuel reprocessing.

提高中厚板淬火炉出炉温度命中率的实践研究

某公司淬火炉因燃气种类变化对燃烧系统进行了改造,改造后出炉温度命中率波动较大,严重影响了产品性能的稳定性。通过对出炉温度命中率主要影响因素的分析,从点火电极的阳极与阴极之间距离变化、UV探头失效分析及内外温差导致烧嘴损坏三个方面提出了解决方案,实现了出炉温度命中率的大幅提升。

日盲型AlGaN紫外阵列探测器研制

针对日盲紫外波段光信号的探测,研制了1 280×1 024/15μm×15μm AlGaN阵列型紫外探测器。像元采用共用N面电极的PIN台面结构,介绍了器件的结构、材料生长和制作工艺,并对器件进行了光电性能测试。结果表明:器件的正向开启电压大于10 V,反向击穿电压大于90 V;0.5 V偏压时单像元暗电流约为0.1 fA,1 V偏压时光谱响应范围为255~282 nm, 270 nm峰值波长响应度约为0.12 A/W。器件实现了日盲紫外成像演示。

TiO_(2)光电化学型紫外探测器

紫外辐射人眼不可见,对人类的健康有利有弊,因此需要对其进行探测。在各种类型的紫外探测器中,光电化学型紫外探测器因其制备简单、响应速度快、价格低廉及可自供能而备受关注。本文利用商用P25纳米小球FTO导电玻璃基底上制备了薄膜光阳极,在此基础上组装了三明治结构的光电化学型紫外探测器。光电测试结果显示在365 nm、光强为35 mW·cm^(-2)的紫外光照射下,器件的开路电压为0.576 V、短路电流密度达到了1.045 mA·cm^(-2),响应上升时间为0.010 s、恢复时间为0.012 s。在周期性紫外光的照射下,器件呈现稳定的、可重复的开关性能。另外,器件在可见光区几乎没有响应,展示其可见光盲特性。最后,器件在5~35 mW·cm^(-2)的光强范围内呈现线性输入输出性能。

HPLC-ELSD-UV法同时测定人体胆结石中胆固醇、胆红素及各种胆酸的含量

目的:建立了人体胆结石中胆固醇、胆红素及各种胆酸的HPLC-ELSD-UV含量测定方法。方法:采用ZORBAX SB-C18(4.6mm×150 mm,5μg)色谱柱,0.1%醋酸溶液(A相)和甲醇(B相)为流动相梯度洗脱,流速:1.6 mL·min-1,紫外检测器(检测波长450 nm)和蒸发光散射检测器联用检测,柱温为室温。结果:测定了16个人体胆结石中胆固醇、胆红素及各种胆酸的含量。胆固醇在0.2204-1.653 mg·mL-1、胆红素在0.536-21.44μg·mL-1、各种胆酸在0.2-1.5 mg·mL-1范围内呈良好的线性关系;平均回收率分别为99.8%,101.5%,96.5%-101.2%,RSD分别为1.86%、1.71%、0.53%-2.14%(n=9);人体胆结石中的胆固醇、胆红素含量大多在776.3-972.5μg·mg-1和0.639-2.981μg·mg-1,各种胆酸未检出。结论:本法操作简便、快速、准确、适用范围广,可用于对人体胆结石中胆固醇、胆红素及各种胆酸的同时测定。

HPLC-UV法检测微生物降解体系中西维因含量

采用高效液相色谱-紫外检测（HPLC-UV）法测定微生物降解体系中西维因含量。根据细菌和霉菌降解体系的不同性质选用适宜前处理方式,以Sepax GP-C_（18）柱（150 mm×4.6 mm,5.0μm）为色谱柱,V（乙腈）∶V（水）=（56∶44）为流动相,流速0.5 m L/min,用紫外检测器于220 nm处检测西维因。结果表明,西维因标准品保留时间为7.922 min,在0.5~100 mg/L范围内线性关系良好,相关系数0.999 1。细菌培养液中西维因平均回收率为102.01%,RSD为0.29%;霉菌培养液中平均回收率为100.76%,RSD为1.22%;最低检测限为0.4mg/L。运用该法测得实验室保藏的细菌菌株A4和B-1在LB培养基中培养2 d对20 mg/L西维因降解率分别为35.72%、38.97%;霉菌菌株M-4和YAT在MM培养基中培养7 d对20 mg/L西维因降解率分别为38.69%、51.40%。该法简单,快速,回收率和精密度高,稳定性好。

Self-powered UVC detectors based on α-Ga_(2)O_(3) with enchanted speed performance

Detectors were developed for detecting irradiation in the short-wavelength ultraviolet(UVC)interval using high-quality single-crystallineα-Ga_(2)O_(3) films with Pt interdigital contacts.The films ofα-Ga_(2)O_(3) were grown on planar sapphire substrates with c-plane orientation using halide vapor phase epitaxy.The spectral dependencies of the photo to dark current ratio,responsivity,external quantum efficiency and detectivity of the structures were investigated in the wavelength interval of 200−370 nm.The maximum of photo to dark current ratio,responsivity,external quantum efficiency,and detectivity of the structures were 1.16×10^(4) arb.un.,30.6 A/W,1.65×10^(4)%,and 6.95×10^(15) Hz^(0.5)·cm/W at a wavelength of 230 nm and an applied voltage of 1 V.The high values of photoelectric properties were due to the internal enhancement of the photoresponse associated with strong hole trapping.Theα-Ga_(2)O_(3) film-based UVC detectors can function in self-powered operation mode due to the built-in electric field at the Pt/α-Ga_(2)O_(3) interfaces.At a wavelength of 254 nm and zero applied voltage,the structures exhibit a responsivity of 0.13 mA/W and an external quantum efficiency of 6.2×10^(−2)%.The UVC detectors based on theα-Ga_(2)O_(3) films demonstrate high-speed performance with a rise time of 18 ms in self-powered mode.

Ultraviolet ZnO Photodetectors with High Gain

Fabrication and characterization of metal-semiconductor-metal ultraviolet （MSM UV） photodetector based on ZnO ultra thin （nano scale） films with Pd Schottky contact are reported. The ZnO thin film was grown on glass substrate by thermal oxidation of preeposited zinc films using vacuum deposition technique. With applied voltage in the range from -3V to 3V, the contrast ratio, responsivity, and detectivity for an incident radiation of 0.1 mW at 365 nm wavelength were estimated. The proposed device exhibited a high gain which was attributed to the hole trapping at semiconductor-metal interface. I-V characteristics were studied and the parameters, such as ideality factor, leakage current, resistance-areaproduct, and barrier height, were extracted from the measured data.

液相色谱法测定化妆品中紫外光吸收剂UV-360的含量

优化高效色谱法测定防晒化妆品中紫外光吸收剂UV-360含量的方法。采用甲醇对化妆品进行萃取后进行分析测定,C18色谱柱(250mm×4.6 mm,5μm)、二极管阵列检测器(1.00m L/min)、检测波长为280nm,流动相为90%异丙醇。结果表明,紫外光吸收剂UV-360在0.001mg/L至0.012mg/L的浓度范围呈良好的线性关系,检出限为0.00106mg/L,回收率在100.8%,相对标准偏差(RSD)3.0%。该方法准确、可靠,可用于防晒化妆品中紫外光吸收剂UV-360的检测。

ZnO基异质结紫外探测器光电特性研究

n-ZnO/p-Si异质结紫外探测器存在响应度低和响应范围广的问题,为了获得更好的紫外探测性能,设计了一种n-ZnO/p-SiC异质结紫外探测器。应用TCAD仿真软件模拟了n-ZnO/p-SiC异质结紫外探测器的光学和电学特性,模拟结果表明:n-ZnO/p-SiC异质结紫外探测器暗电流为10^(-15) A,较n-ZnO/p-Si异质结紫外探测器降低了一个数量级;ZnO/p-SiC探测器响应度高达0.41 A/W,较n-ZnO/p-Si器件提高了156%,且n-ZnO/p-SiC紫外探测器仅对紫外光有响应,有效抑制了n-ZnO/p-Si紫外探测器对可见光的响应。

宽禁带半导体Ga_(2)O_(3)基日盲紫外探测器的研究进展

β-Ga_(2)O_(3)是一种超宽禁带半导体材料,对应太阳光谱的深紫外波段,可用于制备日盲紫外探测器。日盲紫外探测器抗干扰能力强、探测灵敏度高、背景噪声低,在军事和航空航天领域具有极大的应用前景。本文主要介绍Ga_(2)O_(3)材料的基本性质,包括不同的晶相结构及其制备方法,并总结不同结构的Ga_(2)O_(3)器件在日盲紫外探测领域的研究进展。其中,金属-半导体-金属(MSM)结构的Ga_(2)O_(3)器件最为普遍,特别是基于薄膜材料的器件已具备了商业化参数,有望实现产业化应用。基于Ga_(2)O_(3)的异质结和肖特基结日盲紫外探测器也表现出优异的性能,并呈现出自供电特性。此外,薄膜晶体管结构Ga_(2)O_(3)器件结合MSM结构和晶体管结构的工作机制,可获得更大的光增益,适用于微弱信号的探测,成为一种极具潜力的日盲紫外探测器件。

紫外-荧光检测器串联高效液相色谱法测定维生素B_(2)片含量的实验设计

设计一种紫外检测器(UVD)与荧光检测器(FLD)串联的高效液相色谱法(HPLC)测定维生素B2片含量的方法,并应用于实验教学。该实验方案能克服常规HPLC法(单一检测器)存在的缺限,同时实验过程中学生不仅掌握了HPLC的操作,而且能了解UVD和FLD的原理及应用,利于培养学生的综合检测能力和拓展思维能力。