Measurement of w-InN/h-BN Heterojunction Band Offsets by X-Ray Photoemission Spectroscopy

X-ray photoelectron spectroscopy has been used to measure the valence band offset (VBO) of the w-InN/h-BN heterojunction. We find that it is a type-II heterojunction with the VBO being -0.30 +/- A 0.09 eV and the corresponding conduction band offset (CBO) being 4.99 +/- A 0.09 eV. The accurate determination of VBO and CBO is important for designing the w-InN/h-BN-based electronic devices.

The growth of ZnO on bcc-In2O3 buffer layers and the valence band offset determined by X-ray photoemission spectroscopy

This work was supported by the 863 High Technology R&D Program of China (Grant Nos. 2007AA03Z402 and 2007AA03Z451), the Special Funds for Major State Basic Research Project (973 program) of China (Grant No. 2006CB604907), and the National Science Foundation of China (Grant Nos. 60506002 and 60776015). The authors express their appreciation to Dr. Tieying Yang and Prof. Huanhua Wang (Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences) for XRD measurements and helpful discussions.

Band alignment of InN/GaAs heterojunction determined by x-ray photoelectron spectroscopy

The valence band offset (VBO) of the InN/GaAs heterojunction is directly determined by x-ray photoelectron spectroscopy to be 0.94 +/- 0.23 eV. The conduction band offset is deduced from the known VBO value to be 1.66 +/- 0.23 eV, and a type-II band alignment forms at the InN/GaAs heterojunction. (C) 2008 American Institute of Physics.

Determination of wurtzite InN/cubic In2O3 heterojunction band offset by x-ray photoelectron spectroscopy

In2O3 is a promising partner of InN to form InN/In2O3 heterosystems. The valence band offset (VBO) of wurtzite InN/cubic In2O3 heterojunction is determined by x-ray photoemission spectroscopy. The valence band of In2O3 is found to be 1.47 +/- 0.11 eV below that of InN, and a type-I heterojunction with a conduction band offset (CBO) of 0.49-0.99 eV is found. The accurate determination of the VBO and CBO is important for use of InN/In2O3 based electronic devices.

Structural, magnetic properties and photoemission study of Ni-doped ZnO

Nickel-doped ZnO (Zn1-xNixO) have been produced using rf magnetron sputtering. X-ray diffraction measurements revealed that nickel atoms were successfully incorporated into ZnO host matrix without forming any detectable secondary phase. Ni 2p core-level photoemission spectroscopy confirmed this result and suggested Ni hits it chemical valence of 2 +. According to the . We studied the electronic magnetization measurements, no ferromagnetic but paramagnetic behavior was found for Zn0.86Ni0.14O. We studied the electronic structure of Zn0.86Ni0.14O by valence-band photoemission spectroscopy. The spectra demonstrate a structure at similar to 2 eV below the Fermi energy E-F, which is of Ni 3d origin. No emission was found at E-A, suggesting the insulating nature of the film. (c) 2005 Elsevier Ltd. All rights reserved.

Photoemission study of chemisorption and Fermi-level pinning at K/GaAs(100) interface with synchrotron radiation

The adsorption of K on the n-GaAs(I 0 0) surface was investigated by X-ray photoelectron spectroscopy (XPS) and synchrotron radiation photoemission spectroscopy (SR-PES). The Ga3d and As3d core level was measured for clean and K adsorbed GaAs(I 0 0) surface. The adsorption of K induced chemical reaction between K and As, and the K-As reactant formed when the K coverage theta > I ML. The chemical reaction between K and Ga did not occur, but Ga atoms were exchanged by K atoms. From the data of band bending, the Schottky barrier is 0.70 eV. The Fermi-level pinning was not caused by defect levels. The probable reason is that the dangling bonds of surface Ga atoms were filled by the outer-shell electrons of K atoms, forming a half-filled surface state. The Fermi-level pinning was caused by this half-filled surface state. (c) 2004 Elsevier B.V. All rights reserved.

Influence of band bending and polarization on the valence band offset measured by x-ray photoelectron spectroscopy

The influence of band bending and polarization on the valence band offset measured by x-ray photoelectron spectroscopy (XPS) is discussed, and a modification method based on a modified self-consistent calculation is proposed to eliminate the influence and thus increasing the precision of XPS. Considering the spontaneous polarization at the surfaces and interfaces and the different positions of Fermi levels at the surfaces, we compare the energy band structures of Al/Ga-polar AlN/GaN and N-polar GaN/AlN heterojunctions, and give corrections to the XPS-measured valence band offsets. Other AlN/GaN heterojunctions and the piezoelectric polarization are also introduced and discussed in this paper.

ELECTRONIC SPECTROSCOPY STUDIES OF A P2S5NH4OH TREATED GAS(100) SURFACE

Microscopic characteristics of the GaAs(100) surface treated with P2S5/NH4OH solution has been investigated by using Auger-electron spectroscopy (AES) and x-ray photoemission spectroscopy (XPS). AES reveals that only phosphorus and sulfur, but not oxygen, are contained in the interface between passivation film and GaAs substrate. Using XPS it is found that both Ga2O3 and As2O3 are removed from the GaAs surface by the P2S5/NH4OH treatment; instead, gallium sulfide and arsenic sulfide are formed. The passivation film results in a reduction of the density of states of the surface electrons and an improvement of the electronic and optical properties of the GaAs surface.

PHOTOEMISSION-STUDY OF THE INTERFACIAL FORMATION PROCESS AND REACTIONS BETWEEN AL AND HYDROGENATED AMORPHOUS SI

Using photoemission spectroscopy and Auger electron spectroscopy, the interfacial formation process and the reactions between Al and hydrogenated amorphous Si are probed, and annealing behaviors of the Al/a-Si:H system are investigated as well. It is found that a three-dimensional growth of Al metal clusters which includes reacted Al and non-reacted metal Al occurs at the initial Al deposition time, reacted Al and Si alloyed layers exist in the Al/a-Si:H interface, and non-reacted Al makes layer-by-layer growth forming a metal Al layer on the sample surface. The interfacial reactions and element interdiffusion of Al/a-Si:H are promoted under the vacuum annealing.

PHOTOEMISSION-STUDIES OF K-PROMOTED NITRIDATION AND OXIDATION OF THE INP(100) SURFACE USING SYNCHROTRON-RADIATION

The effect of a potassium overlayer on nitridation and oxidation of the InP(100) surface is investigated by core-level and valence-band photoemission spectroscopy using synchrotron radiation. In comparison with the K-promoted nitridation of the InP(110) surface obtained by cleavage in situ, we found that the promotive effect for the InP(100) surface cleaned by ions bombardment is much stronger and that the nitridation products consist of two kinds of complexes: InPNx and InPNx+y. The results confirmed that surface defects play an important part in the promotive effect. Furthermore, in contrast with K-promoted oxidation of InP(100) where bonding is observed between indium and oxygen, indium atoms did not react directly with nitrogen atoms during the K-promoted nitridation of InP(100). (C) 1995 American Vacuum Society.

PHOTOEMISSION-STUDIES OF K-PROMOTED NITRIDATION OF INP(100) SURFACE USING SYNCHROTRON-RADIATION

The effect of molecular nitrogen exposure on the surfaces of InP(100) modified by potassium overlayers is investigated by core-level and valence-band photoemission spectroscopy using Synchrotron radiation. In comparison with InP(110) surface, we found the promotion is much stronger for InP(100) surface due to the central role of surface defects in the promotion; furthermore, in contrast with K-promoted oxidation of InP(100) where the bonding is observed between indium and oxygen, indium atoms did not react directly with nitrogen atoms during the K-promoted nitridation of InP(100).

Interfacial electronic structure of copper phthalocyanine and copper hexadecafluorophthalocyanine studied by photoemission

Electronic structures of the heterojunction between copper phthalocyanine (CuPc) and copper hexadecafluorophthalocyanine (F16CuPc) were studied with ultraviolet photoemission spectroscopy. Band bending and an interface dipole were observed at the interface due to the formation of an electron accumulation layer and a depletion layer in F16CuPc and CuPc, respectively. Such an energy level alignment leads to interesting ambipolar characteristics for application of the CuPc/F16CuPc junction in organic field-effect transistors.

Structural and magnetic properties of insulating Zn1-xCoxO thin films

Cobalt-doped ZnO (Zn1-xCoxO) thin films were fabricated by reactive magnetron cosputtering. The processing conditions were carefully designed to avoid the occurrence of Co precipitations. The films are c-axis oriented, and the solubility limit of Co in ZnO is less than 17%, determined by x-ray diffraction. X-ray photoemission spectroscopy measurements show Co ions have a chemical valance of 2+. In this paper, hysteresis loops were clearly observed for Zn1-xCoxO films at room temperature. The coercive field, as well as saturation magnetization per Co atom, decreases with increasing Co content, within the range of 0.07

Synthesis and characterizations of Al-doped Zn0.95Ni0.05O nanocrystals

Nanocrystalline Zn0.95-xNi0.05AlxO (x = 0.01, 0.02, 0.05 and 0.10) diluted magnetic semiconductors have been synthesized by an autocombustion method. X-ray absorption spectroscopy, high-resolution transmission electron microscopy, energy-dispersive spectrometry and Ni 2p core-level photoemission spectroscopy analyses revealed that some of the nickel ions were substituted for Zn2+ into the ZnO matrix while others gave birth to NiO nanoclusters embedded in the ZnO particles. The Zn0.95Ni0.05O sample showed no enhancement of room-temperature ferromagnetism after Al doping. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Structural and magnetic properties of insulating Zn1-xCoxO thin films

Cobalt-doped ZnO (Zn1-xCoxO) thin films were fabricated by reactive magnetron cosputtering. The processing conditions were carefully designed to avoid the occurrence of Co precipitations. The films are c-axis oriented, and the solubility limit of Co in ZnO is less than 17%, determined by x-ray diffraction. X-ray photoemission spectroscopy measurements show Co ions have a chemical valance of 2+. In this paper, hysteresis loops were clearly observed for Zn1-xCoxO films at room temperature. The coercive field, as well as saturation magnetization per Co atom, decreases with increasing Co content, within the range of 0.07