Deposition: Molecular Beam Epitaxy #2
Quick Specs
- XPS Energy Resolution: 0.80 eV full-width half max on the silver 3d5/2 peak from polycrystalline silver, excited with nonmonochromatic magnesium Kα X-rays.
- XPD Angular Resolution: Full angles of acceptance of ±7° and ±1°
Absolute angular accuracy of ±0.25°.
EMSL's Molecular Beam Epitaxy #2 (MBE 2) system, along with its Molecular Beam Epitaxy #1 (MBE 1) system, is mainly used to grow high-quality epitaxial oxide thin films and nanostructures. Currently, EMSL researchers are using this system for growth and characterization of:
- Copper oxide quantum dots on suitable substrates for photocatalysis applications
- Multilayer electrolyte materials, such as gadolinia-doped ceria and zirconia, for solid oxide fuel cell applications
- Growth of thin film metal oxides for fundamental surface chemistry studies.
MBE 2 was designed and constructed by EMSL researchers as a prototype MBE system for oxide growth before MBE 1 was constructed. Although smaller than its sister system, the MBE 2 system possesses many of the same capabilities—with the exception of optical flux characterization and scanning probe microscopy. MBE 2 also has fewer solid sources (two electron beam and three effusion cells with pneumatic shutters) than MBE 1 (which has four electron beam and three effusion cell solid sources).
MBE 2 is equipped with two quartz crystal oscillators (QCOs—one of them can be placed in the sample position using a linear motion feedthrough) in the MBE chamber and baffles to prevent "cross talk" from the two electron beam evaporation sources. The X-ray photoelectron spectroscopy (XPS) chamber is equipped with XPS, ultraviolet photoemission spectroscopy (UPS), and X-ray photoelectron diffraction (XPD) capabilities that allow researchers to measure detailed compositional and electronic/geometric structural properties of epitaxial films.
System Configuration and Operational Overview
Substrates are loaded into the MBE 2 on transferable sample platens that include a transferable thermocouple. The allowable sample shapes and sizes will accommodate 10.0-mm x 10-mm x 1-mm wafers. The platens are designed to reach a maximum temperature of 1200°C. In addition, the platen can be cooled to approximately -170°C. Temperature measurements can be performed using the thermocople attached to the sample and an infrared pyrometer through a sapphire window.
Once in the MBE chamber, samples can be cleaned by either sputter/anneal cycles or by annealing in the oxygen plasma. Chamber pressures during operation of the plasma, whether during cleaning or deposition, are typically ~2 x 10-6 Torr to ~3 x 10-5 Torr. The gas dosing can be achieved using a calibrated dosing gas inlet system, and the gas composition can be monitored by a quadrupole mass spectrometer. The electron beam evaporators are controlled manually. Two QCOs are available for monitoring metal flux. The effusion cell is controlled by temperature feedback. There is a single pneumatic shutter for the sample. Manually operated shutters can be installed for the electron beam evaporators, provided that the effusion cell is removed from the system. The growth can be monitored in situ by reflection high-energy electron diffraction (RHEED), and the RHEED pattern can be captured and analyzed by a CCD camera and the data acquistion software provided by KSA Associates.
There is heating and cooling (1000°C to -120°C) on the XPS/UPS/XPD manipulator.
Following the necessary training provided onsite by the equipment custodian, researchers can use the MBE 2 system independently or in collaboration with EMSL staff.
All Related Publications Related Publications
- Understanding the nature of surface nitrates in BaO/gamma-Al2O3 NOx storage materials: A combined experimental and theoretical study .
- Reaction of NO2 with a pure, thick BaO film: the effect of temperature on the nature of NOx species formed.
- Symmetry-Driven Spontaneous Self-assembly of Nanoscale Ceria Building Blocks to Fractal Super-octahedra.
- BaO/Al2O3/NiAl(110) Model NOx Storage Materials: the effect of BaO film thickness on the amorphous-to-crystalline Ba(NO3)2 phase transition.
- Influence of samaria doping on the resistance of ceria thin films and its implications to the planar oxygen sensing devices.
