Xu Shi-Hong

X-ray and ultraviolet photoemission study of the formation and band lineup of C60/Si(111) interface

Abstract The interface formation and band lineup of the C 60 /Si(111) are studied using X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). It was found that there was no chemical reaction and diffusion between C 60 overlayer and Si(111) substrate. The results showed that the C 60 /Si(111) interface was abrupt. According to the data of the core-level rigid shift and the top of the valence band, we obtained that the valence band offset ΔE v of C 60 /Si(111) heterojunction was equal to 0.40eV.

VALENCE BAND OFFSET AND INTERFACE FORMATION OF GE/ZNSE(100) STUDIED BY SYNCHROTRON RADIATION PHOTOEMISSION

Abstract The formation and band lineup of the Ge/ZnSe(100) interface have been studied by synchrotron radiation photoemission spectroscopy. Core level intensity measurements from the ZnSe substrate as well as from the Ge overlayer show a two-dimensional deposition of Ge film. Core level spectra indicate that Ge atoms react with Se atoms slightly at the interface. We derive a valence band offset of 1.76±0.1eV for Ge/ZnSe(100).

INTERFACE FORMATION OF Ge/ZnSe(100) AND Ge/ZnS(111) HETEROJUNCTIONS STUDIED BY SYNCHROTRON RADIATION PHOTOEMISSION

The microscopic evolution of interface formation between Ge and II-VI compounds such as ZnSe and ZnS single crystals has been studied by synchrotron radiation photoemission spectroscopy and low energy electron diffraction. Core level intensity measurements from the substrate as well as from the overlayer show a nearly ideal two-dimensional growth mode for the deposition of Ge on ZnSe(100) surface. However, there is a certain deviation from the ideal two-dimensional mode in the case of Ge/ZnS(111) due to the diffusion of substrate atoms into Ge overlayer. Surface sensitive core level spectra indicate that the reaction of Ge with S atoms at Ge/ZnS(111) interfaces is much stronger than that of Ge with Se atoms at Ge/ZnSe(100) interfaces.

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 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.

Electronic Structure in Cd0.96Zn0.04Te Compound: A Synchrotron Radiation Photoemission Study

We have studied the electronic structure of clean CdZnTe (111) compound using high resolution synchrotron radiation photoemission spectroscopy. Surface states were found in Cd, Te 4d core levels and valence band. The valence band measuerment is in good agreement with theoretical calculations using linear muffin-tin orbit method.

Photoelectron spectroscopic study of the effect of Cs intralayer on the band lineup of Ge/InP(100) heterojunction

The formation and band lineup of the Ge/InP(100) interface with or without alkali metal Cs intralayer (IL) are studied by means of x-ray photoemission spectroscopy (XPS) and ultraviolet photoemission spectroscopy (UPS). It is found that the Cs atoms do not react with or diffuse into the substrate and the Ge overlayer. The thin Cs IL will induce an increase of the valence band offset (ΔEv) for the Ge/InP(100) heterojunction. The changes of ΔEv are proportional to the IL thickness and then saturate for IL thickness of about one half of a monolayer of Cs IL. Without the IL, ΔEv of the Ge/InP(100) heterojunction is equal to 0.70eV, and ΔEv with one half of monolayer IL is up to 0.90eV. These results show that the interface dipole plays a major role in the band lineup at the heterojunction interface.

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.