Mn/GaAs(100)界面的形成和化学反应的研究

FORMATION AND CHEMICAL REACTION OF THE Mn/GaAs(100) INTERFACE

利用低能电子衍射(LEED)、X射线光电子能谱(XPS)、电子能量损失谱(EELS)、紫外光电子能谱(UPS),对室温下Mn在GaAs(100)4×1表面的淀积过程进行了研究。研究结果表明,当锰的覆盖度θ≥0.25nm时,LEED图案完全消失,表明Mn没有生长成单晶。LEED,EELS的结果都表明淀积初期是层状生长的。对XPS的Ga2p_(3/2),As2p_(3/2)的峰形、强度进行分析,可以知道在很小的覆盖度下,Mn就与衬底反应。置换出的Ga被局限在离原来的界面约3nm以内的区域内;而As以As-Mn化合物的形式偏析在Mn层的表面。在淀积的后期,Mn在GaAs表面也是层状生长的。UPS的结果直观地支持了XPS的结论。

The interface formation of room temperature deporsited Mn on GaAs(100) (4×1) surface was studied by low energy electron diffraction (LEED), X-ray photoelectron spec-troscopy (XPS), electron energy loss spectroscopy (EELS) and ultra-violet photoelectron spectroscopy (UPS). It was found that above the Mn coverage of 0. 25 nm, the LEED pattern disappeared completely, which indicated that the Mn overlayer did not form single crystalline structure. The layer-by-layer growth mode at the initial stage was proved by the results of both LEED and EELS. By careful study of the intensities and line shapes of the Ga2p3/2 and As2p3/2 core level photoemission spectra, we observed that the exchange reaction between the deposited Mn and the substrate occurred at very early stage. The Ga atoms released by the exchange reaction distributed within a region about 3 nm above the original interface, while the As atoms which combined with Mn to form As-Mn compound segregated on the top of Mn overlayer. The layer-by-layer growth mode persisted until the latest stage of the deposition. Some of the above results were intuitively confirmed by UPS measurements.