Invited Paper SA+AS+MG+SS-TuA7
Hard X-ray Photoelectron Spectroscopy (HAXPES) Investigations of Electronic Materials and Interfaces
Tuesday, October 29, 2013, 4:00 pm, Room 203 C
Photoelectron spectroscopy is a widely used technique that can uniquely measure the chemical and electronic structure of solids. Owing, however, to the historical use of low-energy photons and the resulting limited photoelectron inelastic mean-free path, the technique has found only general application to surfaces and shallow interfaces. With advances in both photon-source and electron-spectrometer instrumentation, hard x-ray photoelectron spectroscopy (HAXPES), where the photon energy is typically in the 2.1 – 10 keV range, has consequently emerged as a powerful tool for studying the bulk and interfacial properties of complex materials systems. In this talk, we will discuss developments of the HAXPES technique at the NIST beamline X24A at the National Synchrotron Light Source for the study of electronic materials. Examples will include nitrogen treatment of HfO2 gate stacks on Si, depth profiling of the HfO2/SiO2 interfaces, Ga and As “out-diffusion” at semiconductor/oxide interfaces, band offsets and Schottky barrier heights at semiconductor/oxide and diamond/metal interfaces, and oxygen vacancies in N doped TiO2 and solid-oxide fuel cells. In all cases, the increased probing depth of HAXPES over traditional lab based XPS is crucial to study the electronic structure of entire overlayers and/or buried interfaces with thicknesses of industrial significance.