Ex Situ Photoelectron Emission Microscopy of Polycrystalline Bismuth and Antimony Telluride Surfaces Exposed to Ambient Oxidation.

The surfaces of textured polycrystalline N-type bismuth telluride and P-type antimony telluride materials were investigated using ex situ photoelectron emission microscopy (PEEM). PEEM enabled imaging of the work function for different oxidation times due to exposure to air across sample surfaces. The spatially averaged work function was also tracked as a function of air exposure time.

Determination of Hafnium Zirconium Oxide Interfacial Band Alignments Using Internal Photoemission Spectroscopy and X-ray Photoelectron Spectroscopy.

Doped ferroelectric HfO is highly promising for integration into complementary metal-oxide semiconductor (CMOS) technology for devices such as ferroelectric nonvolatile memory and low-power field-effect transistors (FETs). We report the direct measurement of the energy barriers between various metal electrodes (Pt, Au, Ta, TaN, Ti/Pt, Ni, Al) and hafnium zirconium oxide (HfZrO, HZO) using internal photoemission (IPE) spectroscopy. Results are compared with valence band offsets determined using the three-sample X-ray photoelectron spectroscopy (XPS) as well as the two-sample hard X-ray photoelectron spectroscopy (HAXPES) techniques.

Engineering the Microstructure and Morphology of Explosive Films Control of Interfacial Energy.

Physical vapor deposition of organic explosives enables growth of polycrystalline films with a unique microstructure and morphology compared to the bulk material. This study demonstrates the ability to control crystal orientation and porosity in pentaerythritol tetranitrate films by varying the interfacial energy between the substrate and the vapor-deposited explosive. Variation in density, porosity, surface roughness, and optical properties is achieved in the explosive film, with significant implications for initiation sensitivity and detonation performance of the explosive material.

Effects of Surface Chemistry and Topology on the Kinesin-Driven Motility of Microtubule Shuttles.

Nanoscale transport using the kinesin-microtubule system has been successfully used in applications ranging from self-assembly, to biosensing, to biocomputation. Realization of such applications necessitates robust microtubule motility particularly in the presence of complex sample matrices that can affect the interactions of the motors with the surface and the transport function. In the present work, we explored how the chemical nature and nanoscale topology of various surfaces affected kinesin-microtubule transport.

Core hole processes in x-ray absorption and photoemission by resonant Auger-electron spectroscopy and first-principles theory.

Electron-core hole interactions are critical for proper interpretation of core-level spectroscopies commonly used as analytical tools in materials science. Here we utilize resonant Auger-electron spectroscopy to uniquely identify exciton, shake, and charge-transfer processes that result from the sudden creation of the core hole in both x-ray-absorption and photoemission spectra. These effects are captured for the transition-metal compounds SrTiO and MoS by fully , combined real-time cumulant, and Bethe-Salpeter equation approaches to account for core hole dynamics and screening.