中国西部农村经济发展面临的挑战及对策

根据中国西部农村自然条件和社会条件 ,分析了西部农村经济发展中面临的问题 ,并提出了相应的对策 :抓住历史机遇 ,转变思想观念 ;改善基础设施 ,发挥设施功能 ;增加资金投放 ,提高投入水平 ;发展文化教育 ,加快人才培育 ;强化政府职能 ,提高管理水平

Dislocations in InAs epilayers grown by MBE on GaAs substrates under various conditions

Using Transmission Electron Microscopy, we studied the misfit and threading dislocations in InAs epilayers. All the samples, with thickness around 0.5 mu m, were grown on GaAs(001) substrates by molecular beam epitaxy under As-rich or in-rich conditions. The As-rich growth undergoes 2D-3D mode transition process, which was inhibited under In-rich surface. High step formation energy under As-deficient reconstruction inhibits the formation of 3D islands and leads to 2D growth. The mechanism of misfit dislocations formation was different under different growth condition which caused the variation of threading dislocation density in the epilayers.