DC characteristics of lattice-matched InAlN/AlN/GaN high electron mobility transistors

Lattice-matched InAlN/AlN/GaN high electron mobility transistors (HEMTs) grown on sapphire substrate by using low-pressure metallorganic chemical vapor deposition were prepared, and the comprehensive DC characteristics were implemented by Keithley 4200 Semiconductor Characterization System. The experimental results indicated that a maximum drain current over 400 mA/mm and a peak external transconductance of 215 mS/mm can be achieved in the initial HEMTs. However, after the devices endured a 10-h thermal aging in furnace under nitrogen condition at 300 ℃, the maximum reduction of saturation drain current and external transconductance at high gate-source voltage and drain-source voltage were 30% and 35%, respectively. Additionally, an increased drain-source leakage current was observed at three-terminal off-state. It was inferred that the degradation was mainly related to electron-trapping defects in the InAlN barrier layer.     

降低汽车尾气中NO_X的技术进展

文章介绍了汽车尾气污染物的危害以及NOX的生成机理,从废气再循环技术、缸内直喷式燃烧技术、代用燃料、电子控制技术、催化还原技术等几个方面,对降低汽车尾气中NOX的排放技术进行了研究。     

Low temperature sintering and performance of aluminum nitride/borosilicate glass

Aluminum nitride （AlN）/borosilicate glass composites were prepared by the tape casting process and hot-press sintered at 950 ℃ with AIN and SiO2-B203-ZnO-Al2O3-Li2O glass as starting materials. We characterized and analyzed the variation of the microstructure, bulk density, porosity, dielectric constant, thermal conductivity and thermal expansion coefficient （TEC） of the ceramic samples as a function of AIN content. Results show that AIN and SiO2-B2O3-ZnO-Al2O3-Li2O glass can be sintered at 950 ℃, and ZnAI204 and Zn2SiO4 phase precipitated to form glass-ceramic. The performance of the ceramic samples was determined by the composition and bulk density of the composites. Lower AlN content was found redounding to liquid phase sintering, and higher bulk density of composites can be accordingly obtained. With the increase of porosity, corresponding decreases were located in the dielectric constant, thermal conductivity and TEC of the ceramic samples. When the mass fraction of AlN was 40%, the ceramic samples possessed a low dielectric constant （4.5-5.0）, high thermal conductivity （11.6 W/（m.K）） and a proper TEC （3.0× 10^-6 K^-1 which matched that of silicon）. The excellent performance makes this kind of low temperature co-fired ceramic a promising candidate for application in the micro-electronics packaging industry.     

细分散B_4C颗粒对Si_3N_4陶瓷的增强与增韧效应

本文通过对不同B4C含量的Si3N4陶瓷的力学性能研究,探讨了B4C相变对Si3N4陶瓷的强度和韧度的影响,分析了各种增强与增韧的机制,并用能量平衡理论讨论了强度和韧度增加的原因.结果表明,利用应力诱导相变效应,可以有效地提高Si3N4陶瓷的弯曲强度和断裂韧度.     

废催化剂回收利用的方法和现状分析

本文首先介绍了废催化剂回收利用的重要意义和现状,然后着重介绍了含贵金属系废催化荆、含钼废催化剂和含钴废催化剂的回收方法和技术。     

用Cl-P_(204)萃淋树脂分离分光光度法测定高钼低铼溶液中的铼

研究了Cl－P_(204)萃淋树脂分离高含量钼溶液中微量铼的性能和条件．建立了一种在高钼低铼下，树脂柱分离硫脲显色分光光度法测定微量铼的方法．     

钼对人体健康的生理效应及其机制研究

钼作为人体必需的微量元素,其在机体内含量的多少将直接影响人类的健康。研究表明,适量的钼对人体各项生命活动具有重要意义,但钼缺乏和钼过量均会引起各种疾病。     

钼蓝比色法测定不同种质何首乌磷脂的含量

目的:探索何首乌的品种选育和质量控制的方法。方法:用钼蓝比色法测定不同种质何首乌的磷脂含量并对结果进行分析。结果:测定的37份不同种质何首乌其磷脂含量差异显著。结论:可利用钼蓝比色法对何首乌的磷脂进行含量测定。     

氮化物硬质薄膜残余应力的研究进展

文章讨论了几种薄膜残余应力测试方法的优缺点,介绍了氮化物薄膜应力沿层深分布趋势的最新研究,偏压和N2分压工艺对薄膜应力的影响及几种调节薄膜残余应力的有效方法．脉冲偏压增大,薄膜残余应力显著增加：N2分压增大,薄膜残余应力显著增加．采用独立变化脉冲偏压或变化N2分压工艺制备的薄膜,其残余应力沿层深分布趋势明显均匀,薄膜残余应力可得到有效调整．     

单纯形优化的示波电位催化动力学法测定痕量钼

Under the optimum experimental conditions (i. e. ,pH = 1.6, cKI = 10.6 mmol/L, cH2O2 = 5.4 mmol/L, cC6H8O6 = 1.30mmol/L) derived from simplex operations, trace molybdenum(Ⅵ) was determined through the agency of its catalytic effect on the reaction of H2O2 with I- in acid medium. The detection limit and linear calibration range of molybdenum were obtained as 0.5 × 10-6 mol/L and 0.5 × 10- 6 ～ 120 × 10- 6 mol/L respectively. This method was appli ed to the examination of the industrial waste water, and the recovery ratios were found to be in the range of 101% and 107%.