The Electronic Materials and Nanostructures Laboratory (EMNLAB) is a group within the physical electronics branch of Electrical Engineering at The Ohio State University. The group focuses on using a wide array of analysis, processing, and growth techniques to investigate the surface, interface, and ultrathin film properties of semiconductors. The group is led by Dr. Brillson and consists of two full-size laboratories that house some of the latest surface analysis equipment.
AES-Auger Electron Spectroscopy-chemical analysis
Atomic Force Microscopy surface morphology analysis
Auger Electron Spectroscopy - Depth Profiling
CLS (Cathodoluminescence Spectroscopy) analysis
Depth Resolved Cathodoluminescence Spectrosopy Analysis
A low temperature (80 K) DRCLS minichamber with Kimball Physics EGL-2022/EPGS-2022 (50 eV-5 keV) electron gun will be connected via vacuum interlocks with the XPS/UPS and MBE chambers. Fiber optics with near - IR to UV transmission efficiency collect and transmit the emitted photons to compact, multiple grating monochromators positioned outside the chamber. A metal evaporator with deposition masks to form 300-500 μm diameter Schottky diodes is also mounted in a connecting vacuum interlocked chamber. Also connected via UHV interlocks is a remote oxygen plasma (ROP) chamber to remove hydrocarbons, remove sub-surface hydrogen, and reduce subsurface oxygen vacancies without degrading rms surface roughness. These facilities enable electronic properties of thin metal overlayers and epilayers to be characterized incrementally during deposition or growth processes. The combination of DRCLS and angle - dependent XPS spectroscopies in the same chamber enables concurrent, nanometer - depth - resolved measurement of band gaps, deep trap levels, and chemical composition.
Dynamic XPS (Photoemission Spectroscopy) analysis
KPFM-Kelvin Probe Force Microscopy-surface analysis
MBE (Molecular Beam Epitaxy) film growth
Molecular beam epitaxy (MBE) growth, processing and characterization are carried out at the Ohio State University's Electronic Materials and Nanostructure's Laboratory. Central to the growth of complex oxides and their interfaces is a recently acquired Veeco GEN 930 oxide MBE system. This growth tool is equipped with nine shuttered effusion cells, a load-locked three-pocket Thermionics electron beam evaporator, a Unibulb RF plasma source for oxygen, and 1-30 keV reflection high energy electron diffraction (RHEED) optics. A 3" substrate manipulator assembly with continuous azimuthal rotation and dual filament heater enables crystal growth to 1200°C at O2 partial pressures up to 10-5 Torr. A load locked entry/exit chamber, a buffer/preparation chamber, and an extension chamber transfer tube assembly permit UHV sample transfer to and from a surface science analysis chamber without exposure to air. The analysis chamber is equipped with XPS, AES, UPS, LEED, and DRCLS to monitor electronic, chemical, and structural properties of the epitaxial oxide films and their interfaces during the growth process and with subsequent thermal and chemical processing.
PL (Photoluminescence Spectroscopy) - Low Temp.
PL (Photoluminescence Spectroscopy) - Room Temp.
The Versaprobe 500 XPS facility uses an Al Kα (1486.6 eV) monochromatized emission line from an Al anode of the X-ray source and spherical capacitor analyzer with 0.477 eV energy resolution and minimum spatial resolution of 18.9 μm for measurements of surface and near-surface chemical composition, chemical bonding, and Fermi level position. An Omicron HIS 13 vacuum UV He lamp (He II photon line = 40.8 eV) is mounted within the XPS analysis chamber in order to perform higher resolution (overall resolution = 0.158 eV (He I)), angle-dependent UV Photoelectron Spectroscopy (UPS) measurements of valence bands, Fermi level positions, and valence band offsets. For thicknesses below a few nanometers, this XPS provides measurements of heterojunction band offset for the semiconductor-on-semiconductor junctions. A differentially-pumped Ar ion gun (<1.2 x10-8 Torr) with energies controllable from <10 eV to 4 keV, focused at the XPS/UPS focal point, positioned and calibrated in-situ with a Faraday cup, permits both surface cleaning as well as introduction of lattice defects with controllable energies and fluences. The XPS/UPS system is connected with our MBE growth chamber through vacuum interconnects and transfer system.
XPS (X-ray Photoemission Spectroscopy) analysis