Nitrogen Adatom Diffusion on a Ga－Rich GaN （0001） Surface

The diffusion of N adatoms on a Ga-rich GaN(O001) surface has been studied using density-functional theory.The configuration of Ga adatoms on a Ga-rich GaN surface has been identified. The first adlayer Ga adatoms are on top of the terminating substrate Ga atoms, and the outmost adlayer Ga adatoms exist randomly at the T4 or H3 sites. A very different diffusivity of N adatoms on a Ga-rich GaN(0001) surface has been found. The excess Ga adatoms on a GaN(0001) surface reduce the diffusion barrier by 0.75eV and influence the migration path. It seems that bilayer Ga adatoms are helpful for N atom diffusion.     

国家同步辐射实验室同步辐射光电子能谱站的新进展

简要地阐述了同步辐射的优越性，介绍了国家同步辐射实验室光电子能谱站与光束线的设备，综述了国内主要用主站工作人员在金属／半导体界面等方面所开展的工作和一些结果。     

A STUDY ON ABSORPTION OF Na ATOMS ON Si(100) 2×1 SURFACES WITH DV-Xα METHOD

The Na absorption on Si(100) 2×1 surface is studied with quantum chemistry molecular cluster method. The calculated results show that the most favourable absorption site of Na is the cave site and the charge transfer of Na atom to Si is large when the Na coverage is smaller than 0.5 monolayer (ML). A Na chain is formed along the cave sites at the 0.5 ML Na coverage, the charge transfer then becomes small. The calculated density of states show that the Na atoms are metallic along the chain. At 1 ML coverage, the Na atoms occupy both the cave and pedestal sites and form a double-layer. There is a charge transfer of 0.5e from each Na atom to the Si surface. The calculated surface energy shows that the saturation absorption of Na on Si surface is 1 ML.     

Na在Si(111)表面(3×1)有序吸附结构的光电子能谱研究

分析了Si(111)7×7表面上Na(3×1)有序吸附的同步辐射光电子能谱的变化,并与Paggel等的扫描隧道显微镜和光电子能谱比较,得出Na吸附在类余留原子(rest atom)的位置,支持Mnch的模型,与室温下无序吸附Na的光电子能谱相比较,得出Na-Si界面肖特基势垒形成是由Na与Si原子之间的相互作用决定,与表面构形是否有序关系不大,势垒高度与MIGS理论预计值相符。     

SOFT-X-RAY PHOTOEMISSION STUDY OF Mn/GaP(100) INTERFACE

The interface formation and electronic structures of the Mn/GaP(100) interface are studied with synchrotron radiation photoemission, At the early stage of Mn deposition, Mn covers the whole GAP(100) surface. With the increase of coverage, Ga atoms can be exchanged by Mn atoms and diffuse into the Mn overLaycr. However, P atoms remain always near the interracial region. A sigaificant difference of the electronic structures is observed between the ultra-thin and the thick Mn films. The explanations for this are given in the text.     

中性(NH4)2S溶液钝化GaAs(100)表面的研究

采用同步辐射光电子能谱(SRPES)结合扫描电子显微镜(SEM)和称量法，研究了中性(NH₄)₂S溶液钝化GaAs(100)表面，并与常规(NH₄)₂S碱性溶液钝化方法进行了比较- SRPES结果表明该处理方法可以产生较厚的Ga硫化物层和较强的Ga—S键，Ga的硫化物有好的稳定性-称量法表明该方法有更低的腐蚀速率-SEM结果表明该方法钝化处理的GaAs表面所产生的腐蚀坑数目少，直径小- 关键词：     

Ge/ZnS(111)异质结能带偏移的同步辐射光电子能谱研究 *

利用同步辐射光电子能谱研究了Ge/ZnS(111)异质结界面的能带连接问题.芯能级谱显示出Ge原子与S原子在界面处存在反应.利用芯能级谱及价带谱技术,测量了该异质结的价带偏移.对于衬底温度为200℃条件下生长的异质结,其价带偏移为l.94士0.leV;而室温条件下生长的异质结,则为2.23土0.leV该实验结果与一些理论计算值进行比较,符合得较好.     

Na/Si(111)3×1表面的NEXAFS研究

利用同步辐射光源测量Na2s二次电子部分产额谱得到Na诱导Si（111）3×1结构的近边Ｘ射线吸收精细结构（NEXAFS）谱，并用原子集团多重散射方法对几种可能的模型进行计算，与实验结果比较，认为Na/Si（111）3×1吸附结构与Mnch模型相一致．Na原子吸附在Si的顶位，Na—Si键长为0.3nm． 关键词：     

稀土金属Sm/Si(100)2×1界面形成电子结构的同步辐射光电子能谱研究

利用同步辐射芯能级和价带光电子能谱研究了室温下Ｓｍ／Ｓｉ（１００）２×１界面的形成与电子结构．实验结果表明，膜生长有几个不同阶段，分别为Ｓｍ原子聚集（Θ＜０.５ＭＬ）、反应扩散（０.５ＭＬ≤Θ≤４—６ＭＬ）和金属Ｓｍ膜生长．与Ｓｉ（１１１）７×７相比，Ｓｍ在Ｓｉ（１００）２×１的界面反应和扩散都得到加强．结合理论模型，讨论了该界面的形成与界面结构