引进CBE模式 探索化工职业能力培养

ＣＢＥ模式是近年来广泛被北美国家采用的一种职业技术教育模式，贵州省化工学校于１９９８年引进该模式，对工业分析专业的相关课程进行教改。本文从ＣＢＥ模式的内涵到ＣＢＥ模式的引进实践阐述了化工职业能力培养的新途径。     

化学束外延及其在半导体材料与器件中的应用

本文介绍了薄膜晶体生长的最新技术--化学束外延(CBE),通过与分子束外延(MBE)和金属有机化学汽相沉积(MOCVD)技术的比较,说明了这一新技术的基本概念,生长动力学以及在半导体材料和激光器件方面的应用.     

半导体激光器的制造新技术

半导体激光器是激光器中的一种,它的制造技术有分子束外延、液相外延、金属有机物化学气相淀积、低压金属有机物化学气相淀积和化学束外延等.结果表明,器件特性与制备方法有关.例如:利用金属有机气相外延生长的GaAs/GaAlAs异质结,可以制造高精致的大功率激光器,其波长为780～880nm.用具有特殊波导特性的质量阱(QW)结构能满足大功率需要.各种参量包括这些层的结构和配合以及多层结构的光、电特性,通过该方法大面积生长外延层而达到最佳化.本文重点介绍上述技术的生长机理、实验系统简图、典型工艺以及在器件制造上的应用.     

Structural and optical properties of GaxIn1−xP layers grown by chemical beam epitaxy

Chemical beam epitaxial (CBE) Ga_xIn_1?xP layers (x≈0.5) grown on (001) GaAs substrates at temperatures ranging from 490 to 580°C have been investigated using transmission electron diffraction (TED), transmission electron microscopy, and photoluminescence (PL). TED examination revealed the presence of diffuse scattering 1/2{111}_B positions, indicating the occurrence of typical CuPt-type ordering in the GaInP CBE layers. As the growth temperature decreased from 580 to 490°C, maxima in the intensity of the diffuse scattering moved from ½{111}_B to ½{?1+δ,1?δ,0} positions, where δ is a positive value. As the growth temperature increased from 490 to 550°C, the maxima in the diffuse scattering intensity progressively approached positions of $\frac{1}{2}\{\bar 110\} $ , i.e., the value of δ decreased from 0.25 to 0.17. Bandgap reduction (～45 meV) was observed in the CBE GaInP layers and was attributed to the presence of ordered structures.     

创建CBE模式 办出高工专教育特色

如何办出高等工程专科教育的特色是当前教育界普遍关心的问题。作者根据一切从实际出发的原则,选择机械加工工艺专业为教改试点专业。提出以下的基本思路:走高等职业教育的路子,创CBE(符合国情的能力本位教育)模式,集国内外先进有用的教育经验,达适合生产第一线技术工作要求的效果。在此基础上、作者探讨了教改的方法和步骤。     

用乌桕脂生产类可可脂的研究进展和前景

论述了与天然可可脂结构相近的乌桕脂的经济价值,及国内外类可可脂生产技术的进展,作者结合实践经验指出用乌桕脂生产类可可脂需要解决的技术难题,分析了国产类可可脂的市场前景,认为借助边缘科学用乌桕脂制取类可可脂替代昂贵的进口产品的技术难题均可以解决。     

Growth characteristics of hydride-free chemical beam epitaxy and application to GaInP/GaAs heterojunction bipolar transistors

We report on the complete characterization of a hydride- and hydrogen-free chemical beam epitaxy (CBE) process for the realization of GaAs/GaInP heterojunction bipolar transistors. Alternative group V sources tertiarybutylarsine, tertiarybutylphosphine, and trisdimethylaminoarsenic are used instead of traditionally employed AsH₃ and PH₃. A very high degree of reproducibility of growth parameters (fluxes, substrate temperature, doping levels) is demonstrated. Total defect densities lower than 10 def/cm² are routinely obtained. Large-area GaInP/GaAs heterojunction bipolar transistors (HBTs) show a high current gain of 225 for base sheet resistance of 400 ohm/sq. The devices also exhibit excellent high-frequency characteristics. A cut-off frequency of 48 GHz and a maximum oscillation frequency of 60 GHz have been obtained. These results demonstrate the high potential capability of CBE for high-throughput GaInP/GaAs HBT production.     

A novel synthetic route to ether-Free metal alkyl precursors

A new synthetic route to metal alkyl precursors has been developed, eliminating ether solvents which have been shown to result in unintentional oxygen incorporation in epitaxial AlGaAs layers. The synthesis is performed in a trialkylamine solvent and the need for an additional adduct purification step is eliminated. The products of triisopropylgallium synthesis solvated by either ethyldimethylamine or triethylamine have been assessed as potential growth precursors for chemical beam epitaxy by¹H NMR spectroscopy, vapor pressure measurements and GaAs growth rate measurements.     

基于CBE/DACUM的“电子电路装配实习”课程教学改革

从CBE/DACUM角度分析电子电路装配实习课程的能力定位,以及课程实习中存在的问题。根据课程实习的能力定位要求,提出以先进的CBE/DACUM理论为指导;通过编制课程DACUM表,明确课程工作任务和能力要求,从而形成新的课程目标、任务、内容,改革传统教学方式,创新技能培养模式。