仿生气体测量系统——电子鼻

电子鼻是仿照生物的嗅觉系统所设计出来的一个用于测量气体中的化学成分的系统。同以往由单个气体传感器所构成的气体测量系统相比,它从结构上、信号处理的方法上以及使用上都有许多不同的特点。主要介绍了电子鼻的应用、结构以及同传统的气体测量系统的不同点。     

Fabrication and characterization of all-oxide heterojunction p-CuAlO2 + x/n-Zn1 − xAlxO transparent diode for potential application in “invisible electronics”

Transparent p-n heterojunction diodes have been fabricated by p-type copper aluminum oxide (p-CuAlO_2 + x) and n-type aluminum doped zinc oxide (n-Zn_1 − xAl_xO) thin films on glass substrates. The n-layers are deposited by sol-gel-dip-coating process from zinc acetate dihydrate (Zn(CH₃COO)₂·2H₂O) and aluminum nitrate (Al(NO₃)₃·9H₂O). Al concentration in the nominal solution is taken as 1.62 at %. P-layers are deposited onto the ZnO:Al-coated glass substrates by direct current sputtering process from a prefabricated CuAlO₂ sintered target. The sputtering is performed in oxygen-diluted argon atmosphere with an elevated substrate temperature. Post-deposition oxygen annealing induces excess oxygen within the p-CuAlO_2 + x films, which in turn enhances p-type conductivity of the layers. The device characterization shows rectifying current-voltage characteristics, confirming the proper formation of the p-n junction. The turn-on voltage is obtained around 0.8 V, with a forward-to-reverse current ratio around 30 at ± 4 V. The diode structure has a total thickness of 1.1 μm and the optical transmission spectra of the diode show almost 60% transmittance in the visible region, indicating its potential application in ‘invisible electronics’. Also the cost-effective procedures enable the large-scale production of these transparent diodes for diverse device applications.     

SrTiO3双功能陶瓷的施主掺杂研究

研究了２５％Ｎ２＋７５％Ｈ２（体积分数）强还原烧结气氛下施主添加剂Ｎｂ２Ｏ５、Ｌａ２Ｏ３对ＳｒＴｉＯ３双功能陶瓷半导化的作用规律，结果表明随着添加量的增大，Ｎｂ２Ｏ５掺杂试样的表观电阻率单调下降，而Ｌａ２Ｏ３掺杂试样的表现电阻率呈“Ｕ”形曲线，研究了在Ｌａ２Ｏ３高、低两种添加量下，烧结温度对半导化的作用规律，实验结果表明随着烧结温度的升高，高掺杂试样的表观电阻率逐上升，而低掺杂试样逐渐下降，在ＸＲ     

Synthesis and electroluminescent properties of π-conjugated copolymer based on 10-hexylphenothiazine and aromatic 1,2,4-triazole

A new polymer, poly((10-hexyl-3,7-phenothiazine)-alt-(4-(4-butyl-phenyl)-3,5-diphenyl-4H-[1,2,4]triazole)-3,5-diyl) (PT-TAZ), has been synthesized. In order to improve electron injection/transporting ability, we introduce electronegative 1,2,4-triazole group in the backbone. We also synthesized poly(10-hexylphenothiazine-3,7-diyl) (PT) to compare the physical properties with PT-TAZ. The photoluminescence (PL) maximum wavelength, the band gap energy, and the HOMO energy level of PT-TAZ film were 509 nm, 2.67 eV, and −5.06 eV, respectively, which are very comparable to those of PT. The maximum efficiency and brightness of the electroluminescent (EL) device based on PT-TAZ were 0.247 cd/A and 771 cd/m², respectively, which were significantly higher than those of the device based on the polymer without 1,2,4-triazole (TAZ) as a repeat unit (PT) (1.05 × 10⁻⁴ cd/A and 4.4 cd/m²). This is because TAZ unit improves the electron transporting ability in the emissive layer. The turn-on voltage of brightness of the device based on PT-TAZ was 5.0 V, which was slightly higher than that of the based on PT (4.5 V). This is because the ionization potential of PT-TAZ is very similar to that of PT.     

AlGaSb/GaSb quantum wells grown on an optimized AlSb nucleation layer

Five-period AlGaSb/GaSb multiple quantum wells (MQW) are grown on a GaSb buffer.Through optimizing the AlSb nucleation layer,the low threading dislocation density of the MQW is found to be (2.50±0.91)×108cm-2 in 1-μm GaSb buffer,as determined by plan-view transmission election microscopy (TEM) images.High resolution TEM clearly shows the presence of 90°misfit dislocations with an average spacing of 5.4 ran at the AlSb/GaAs interface,which effectively relieve most of the strain energy.In the temperature range from T = 26 K to 300 K,photoluminescence of the MQW is dominated by the ground state electron to ground state heavy hole (el-hhl) transition,while a high energy shoulder clearly seen at T > 76 K.can be attributed to the ground state electron to ground state light hole (e1-lh1) transition.     

Force‐Driven Single‐Atom Manipulation on a Low‐Reactive Si Surface for Tip Sharpening

A single atomic manipulation on the delta‐doped B:Si(111)‐()R30° surface using a low temperature dynamic atomic force microscopy based on the Kolibri sensor is investigated. Through a controlled vertical displacement of the probe, a single Si adatom in order to open a vacancy is removed. It is shown that this process is completely reversible, by accurately placing a Si atom back into the vacancy site. In addition, density functional theory simulations are carried out to understand the underlying mechanism of the atomic manipulation in detail. This process also rearranges the atoms at the tip apex, which can be effectively sharpened in this way. Such sharper tips allow for a deeper look into the Si adatom vacancy site. Namely, high‐resolution images of the vacancy showing subsurface Si dangling bond triplets, which surround the substitutional B dopant atom in the first bilayer, are achieved.     

电压敏电容双功能元件制备

为提高元件半导化原理并提高元件的氧气灵敏度,对以SrTiO3为基材的样品分别在强还原气体条件和大气条件下的N型电压敏、电容双功能元件和P型氧气敏感元件,分别测试了N型元件的压敏电压U1mA等电参数和P型元件在不同的温度下的阻温特性、氧敏特性,并进行了TPD测量。研究表明氧空位是在SrTiO3晶体中杂质扩散、实现半导化的重要条件,因此控制氧空位的浓度成为制备钙钛矿型半导体功能陶瓷元件的重要因素;还原气氛烧结产生的氧空位是材料实现N型半导化的重要手段;受主杂质所产生的氧空位促进了环境氧与晶格氧的交换,是材料实现P型半导化的重要手段,也提高了元件的氧气灵敏度。     

钽阳极氧化膜的半导体性研究

用电容测量技术和电化学阻抗技术研究了高纯钽丝在稀磷酸(质量分数为0.01%,0.10%和1.00%)、氨水(pH=11)和饱和CO2水溶液(pH=4)中阳极氧化形成的氧化钽膜在酸性缓冲液(pH=2)中的半导体性和阻抗特性.实验结果表明,来自非磷酸系的阳极氧化钽膜呈现出双极性(p-n)半导体结构特征,而来自磷酸系的则表现...     

SnO2半导体陶瓷酒敏元件 选择性和欧姆接触研究

在SnO_2主体材料中添加某种硝酸盐溶液浸泡过的α-Al_2O_3,可制成对乙醇蒸汽灵敏度高,对H_2,CO,CH_4和汽油蒸汽灵敏度很低,即选择性好的酒敏元件。采用金属-n~+-n半导体结构来实现金属电极和SnO_2半导体陶瓷之间的欧姆接触,能有效地抑制元件的金-半接触所引起的不良影响,对于提高元件性能的一致性和成品率有重要作用。本文研究了硝酸盐溶液浓度和元件灵敏度、选择性、最佳工作温度的关系。研究了不同结构的金属电极-SnO_2半导体陶瓷接触对元件性能的影响。     

Photoelectrolytic oxidation of organic species at mesoporous tungsten trioxide film electrodes under visible light illumination

Operation of a photoelectrolyser fitted with a semitransparent semiconducting WO₃ film photoanode is described. Due to its band-gap energy of 2.5 eV, the photoresponse of the WO₃ electrode extends into the blue part of the visible spectrum up to 500 nm. The WO₃ photoanode exhibits particularly high incident photon-to-current efficiencies for the oxidation of several organic species with the maximum occurring at ca. 400 nm. Experiments conducted under simulated AM 1.5 solar illumination demonstrated efficient photodegradation of a variety of organic chemicals including small organic molecules as well as EDTA and anthraquinonic Acid Blue 80 dye. Although, due to the inherent mass transport limitations, the described device appears best suited to the treatment of industrial wastewater containing from 100 ppm to few g L⁻¹ of impurities, almost complete removal of organic carbon was observed in several photoelectrolysis runs. This is apparently associated with the concomitant photooxidation of sulphate-based supporting electrolyte resulting in the formation of a powerful chemical oxidant-persulphate.