Electronic and electrical properties of functional interfaces studied by hard X-ray photoemission (original) (raw)
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Applied Physics Letters, 2006
A 1.0 nm silicon nitride ͑SiN͒ layer can prevent reaction between HfO 2 and Si completely. In this case, the interface state spectra obtained from x-ray photoelectron spectroscopy measurements under bias have two peaks above and below the midgap, attributable to Si dangling bonds interacting weakly with an atom in SiN, indicating a high atomic density of the SiN layer. When a HfO 2 layer is deposited on a 1.0 nm SiO 2 layer, the SiO 2 thickness increases to 1.6 nm. For this structure, one interface state peak is present near the midgap, attributable to isolated Si dangling bonds, indicating a low atomic density.
Journal of Computational and Theoretical Nanoscience, 2009
Standardization of an analytical procedure for bonding structure and thickness simulation of nanoscaled ultra thin films was established using the theoretical background of angle-resolved X-ray photoelectron spectroscopy (ARXPS). A structure simulation using ARXPS was designed and a software program with java language was provided for application to a high-k dielectric multilayer system. A thickness simulation was applied to a high-k dielectric layer on semiconductor system of about 2-3 nm Gd 2 O 3 /GaAs and compared to experimental results. Multilayer structure of high-k binary oxide system (HfO 2 and Al 2 O 3 was simulated by photoelectron flux ratio change and their multilayer stacking structures were analyzed with different each layer thickness.
Applied Surface Science, 1993
The dependence of Schottky barrier formation on surface and interface preparation offers several broad avenues for understanding electronic structure and charge transfer at metal/semiconductor junctions. Interface cathode-and photoluminescence measurements reveal that electrically active deep levels form at III-V and II-VI compound semiconductor surfaces and metal interfaces which depend on temperature-dependent surface stoichiometry and reconstruction, chemical interaction, as well as surface misorientation and bulk crystal quality. These interface states are discrete and occur at multiple gap energies which can account for observed band bending. Characteristic trends in such deep level emission with interface processing provide guides for optimizing interface electronic behavior. Correspondingly, photoemission and internal photoemission spectroscopy measurements indicate self-consistent changes in barrier heights which may be heterogeneous and attributable to interface chemical reactions observed on a monolayer scale. These results highlight the multiple roles of atomic-scale structure in forming macroscopic electronic properties of compound semiconductor/ metal junctions.
AIP Advances, 2013
MOS devices based on III-V semiconductors and thin high-k dielectric layers offer possibilities for improved transport properties. Here, we have studied the interface structure and chemical composition of realistic MOS gate stacks, consisting of a W or Pd metal film and a 6-or 12-nm-thick HfO 2 layer deposited on InAs, with Hard X-ray Photoemission Spectroscopy. In and As signals from InAs buried more than 18 nm below the surface are clearly detected. The HfO 2 layers are found to be homogeneous, and no influence of the top metal on the sharp InAs-HfO 2 interface is observed. These results bridge the gap between conventional photoemission spectroscopy studies on various metal-free model samples with very thin dielectric layers and realistic MOS gate stacks. C 2013 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
Probing surfaces and interfaces in complex oxide films via in situ X-ray photoelectron spectroscopy
Journal of Materials Research
Emergent behavior at oxide interfaces has driven research in complex oxide films for the past 20 years. Interfaces have been engineered for applications in spintronics, topological quantum computing, and high-speed electronics with properties not observed in bulk materials. Advances in synthesis have made the growth of these interfaces possible, while X-ray photoelectron spectroscopy (XPS) studies have often explained the observed interfacial phenomena. This review discusses leading recent research, focusing on key results and the XPS studies that enabled them. We describe how the in situ integration of synthesis and spectroscopy improves the growth process and accelerates scientific discovery. Specific techniques include determination of interfacial intermixing, valence band alignment, and interfacial charge transfer. A recurring theme is the role that atmospheric exposure plays on material properties, which we highlight in several material systems. We demonstrate how synchrotron studies have answered questions that are impossible in lab-based systems and how to improve such experiments in the future. Dr. Ryan Comes is an experimental condensed matter and materials physicist and has been an assistant professor of physics at Auburn University since 2016. At Auburn, he is the principal investigator of the Films, Interfaces, and Nanostructures of Oxides (FINO) Lab. The group's research focuses on the synthesis and characterization of complex oxide thin films and nanostructures through molecular beam epitaxy deposition and in situ X-ray photoelectron spectroscopy.
Reviews on advanced materials science
In this contribution we present for the first time simultaneous combination of Surface X- Ray diffraction (SXRD) and Hard X-Ray photoelectron spectroscopy (HAXPES, photoelectrons with kinetic energy up to 15 KeV). Thanks to the simultaneous capability to detect the diffracted photons and the ejected photoelectrons, the developed experimental set-up offers a unique op- portunity to obtain, on the same sample region and under identical experimental conditions, struc- tural, electronic and chemical properties of the studied systems. Due to the high penetration depth of X-rays and the large escape depth of high energy photoelectrons (15 KeV kinetic energy) sur- faces, bulk and buried interfaces are accessible in a non-destructive way. Its implementation at the Spanish CRG beamline (SpLine) at the European synchrotron radiation facility (ESRF) offers an exceptional tool capable to determine composition and structural profiles over a depth of several 10s of nanometers. A huge 2S+3D diffra...