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A sulfur passivation method for GaAs, CH3CSNH2 treatment has been developed. It is quite effective for removing the surface oxide layer and forming the sulfide passivation layer on GaAs surface, with sulfur atoms bound with Ga and As atoms. After being annealed, a stable sulfur passivation layer is formed. The enhancement of PL intensity reveals the reduction of surface non-radiative recombination and the density of surface states. Moreover, the investigation has been made for the role of S-passivation on interfacial interaction between magnetic overlayer and GaAs. The interdiffusion of As, Ga into overlayer is effectively inhibited, and the magnetization of Fe overlayers is enhanced. In addition, a relationship has been found between the surface chemical structure of the substrates and the magnetic property of overlayers.

Ferromagnetic resonance (FMR) has been used to investigat the magnetism of Fe overlayer on S-passivated GaAs(100) pretreated by CH3CSNH2. Comparing with the magnetism of Fe overlayer on clean GaAs(100), we find that sulfur passivation can prevent As diffusion into Fe overlayer and weaken the interaction of As and Fe. It results in enhancing the magnetism of Fe overlayer on GaAs(100). We also investigate the effects of the pre-annealing of S- passivated GaAs(100) substrate on the magnetism of Fe overlayers. The results show that the maximum effective magnetization can be obtained at annealing temperature of 400 °C. According to the experimental results of synchrotron radiation photoemission, it can be explained by the change of chemical composition and surface structure of the passivation layer on GaAs(100) surface after the annealing.

By using synchrotron radiation photoelectron spectroscopy, the band lineup of Ge/CdTe(111) interfaces grown at different temperatures have been measured. Experimental studies show that the valence band offset of Ge/CdTe(111) interface grown at room temperature is 0.88?0.1 eV, which agrees well with previously reported value. While as for the interface grown at 280?C, an obvious reduction of valence band offsets is observed and attributed to the effect of different interface dipole.

The formation of Gd/Cr interface, the growth mechanism and electronic structure of Gd overlayers were investigated by synchrotron radiation photoemission. It is shown that Gd adatoms interact with the Cr substrate weakly. A lower deposition rate of the Gd overlayer (1.0 A/min) favors the smooth growth of Gd/Cr interface. However, higher deposition rate (6.0 A/min) leads to the cluster growth of the Gd overlayer and the presence of a "two-peak" feature of Gd 4f emission. We correlate this feature with the different coordination number of surface atoms derived from cluster- induced surface roughness.

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 overlayer. However, P atoms remain always near the interfacial region. A significant 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.

We have developed a new method to treat GaAs (100) surface by CH3CSNH2/NH4OH solution Synchrotron Radiation Photoemission Spectroscopy (SRPES) and X-ray Photoemission Spectroscopy (XPS) have been used to investigate the chemical states and electronic states of the passivated GaAs (100) surface. The results show that the sulfides of Ga and As were formed on CH3CSNH2/NH4OH solution treated GaAs(100) surface . and the oxides of Ga and As were removed . The treatment has an apparently passivating role for the GaAs. After annealing for the passivated surface , band bending effect was observed and the offset of 0.22 eV toward the higher binding energy was obtained this meant that the densenty of the states of GaAs surface was decreased.

The behavior of interface formed by growing this Sm film on the Ｓｉ（１００）２×１ substrate at room temperature has been investigated by cove level and valence band photoemission using synchrotron radiation. The experimental results show the existence of distinct stages corresponding to chemisorption and agglomeration of Sm atoms（coverage Θ＜０.５ＭＬ）,reactive interdiffusion （０.５ＭＬ≤Θ≤４—６ＭＬ）, and growth of metallic Sm. Compared to Ｓｉ（１１１）７×７ the reactivity of Sm on the Ｓｉ（１００）２×１ substrate is enhanced and a greater tendency for interdiffusion of Sm and Si is observed. Also we have discussed the interface formation and the interface profile carefully.