Facilities

INSTRUMENTATION AND FACILITIES

Deposition

Structural Characterization

Measurement of Physical Properties

General Support Facilities

DEPOSITION

Molecular Beam Epitaxy (MBE)

A Perkin­Elmer 433­S MBE system, consisting of five separate chambers for substrate entry, preparation, deposition, analysis, and experimentation. The deposition chamber contains two single-hearth and one four-hearth electron beam guns with optical, ionization, and quartz crystal rate controllers, four Knudsen cells with ports for four others, and an 1100 °C substrate heater. Also included are RHEED and LEED systems with CCD cameras for image acquisition and a quadrupole mass spectrometer. The analysis chamber contains Auger, ISS, and angle-resolved XPS, an 800 °C heater, a differentially pumped ion gun for depth profiling and substrate etching, and a port for later addition of UPS. The experimentation chamber contains a 3 kG magnet and optical ports for in situ SMOKE measurements on magnetic materials. The preparation, deposition, analysis and experimentation chambers all operate in the 10-11 torr range. This MBE system is located in a class 1000 clean room, with substrate entry in a class 10 environment. This system was obtained with funding from the AFOSR University Research Initiative Program.

A second, Riber 1000, MBE system, consisting of four separate chambers for substrate entry, deposition, analysis and experimentation. The deposition chamber contains seven Knudsen cells and one mini-electron beam evaporator for depositing dopants, and a substrate manipulator with an 800 °C heater. Also included are 30 keV RHEED with CCD camera and a quadrupole mass spectrometer. The analysis chamber contains scanning Auger and SIMS. The experimentation chamber contains an electromagnet, substrate goniometer, and optical parts for in situ light scattering studies. These three chambers operate in the 10-10 torr range. This MBE system is located adjacent to the other one in a class 1000 clean room. This system was donated by Hughes’ Malibu Research Laboratory.

A third, custom-built MBE system consisting of four chambers for substrate entry, deposition, characterization, and Brillouin light scattering. The deposition chamber contains two high temperature Knudsen cells with a port for a third, a 900 °C sample heater, 20 keV RHEED, and a port for a Be window for in situ x-ray diffraction. The analysis chamber contains an atomic resolution UHV STM/AFM. The light scattering chamber has a variable-temperature (55–1450 K) five-axis substrate manipulator optically connected to an ex situ Sandercock tandem six-pass Fabry-Perot interferometer. These three chambers operate in the 10-11 torr range. The entire system sits on a vibration isolation platform, and was obtained with funding from DARPA.

Sputtering

A diffusion ­pumped, high­rate sputtering system with three magnetically­ enhanced­plasma sputter guns. The chamber has a base pressure 5×10-8 torr, and is equipped with a quadrupole mass spectrometer and a number of ports for analytical equipment. The depositions are controlled by a microprocessor and servo­motor system that control the dwell time of the substrates over each gun, rotation rate to the next gun, opening and closing sequence of shutters, etc. to ±0.01% accuracy. Active feedback of the power to each gun and Ar gas flow rate in this system controls individual layer thicknesses to a demonstrated precision of better than ±0.3%.

A second diffusion­pumped, high­rate sputtering system with one conventional and two magnetically­enhanced­plasma sputter guns. The chamber has a base pressure 1×10-7 torr, and contains an access port and manipulator mechanism for transferring samples directly to a portable high vacuum station (10-6 torr). The microprocessor controls, gas flow regulation, etc. are the same as for the other high-rate sputtering system.

A third, cryo-pumped, large-target (8″ diameter) sputtering system for high uniformity over large substrate areas. The chamber has a base pressure 1×10-7 torr. This system was donated by Eastman Kodak.

Evaporation

A general-purpose, diffusion-pumped, four-hearth electron beam gun evaporator, with quartz crystal rate monitor. The chamber has a base pressure 5×10-7 torr.

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STRUCTURAL CHARACTERIZATION

X-Ray Diffraction

We have a Rigaku 18 kW rotating anode, and two Philips/Norelco 2 kW power bases with Co, Cu, Fe, Mo, and W x­ray tubes, with the following diffractometers:

Two wide­range goniometers, both with graphite diffracted beam monochromators, with scan range ­28° < 2 < +165° for precise lattice constant measurements, studies of crystalline structure, orientation and texture. One diffractometer is controlled by an IBM PC which also includes search/match software with a complete set of ICDD files on CD-ROM.

Computer-controlled Huber four-circle diffractometer with parallel incident and diffracted beam monochromators and calibrated attenuator wheel for high-angle rocking curves and off-axial x-ray studies and for diffraction measurements directly from multilayers for angles 0.1° < 2 < 10° and for intensities varying by >107.

Computer-controlled Huber Seemann­Bohlin/Guinier diffractometer with incident beam Ge crystal focussing monochromator for precision studies of crystalline structure, crystallite size, orientation, texture, and epitaxy of films as thin as 100 Å.

5 cm radius wide­film Debye­Scherrer (“Read”) camera for preferred orientation and epitaxy studies of thin films.

5.73 cm diameter Debye­Scherrer camera for routine determination of lattice constants of powder specimens.

11.46 cm diameter Debye­Scherrer camera for precision lattice constant measurements of powder specimens.

5×7 in. wet­film flat plate Laue camera for determination of crystalline symmetry (in both transmission and reflection geometry).

4×5 in. Polaroid flat plate Laue camera for rapid determination of crystalline symmetry (in both transmission and reflection geometry).

Electron Microscopy (TEM and SEM)

JEOL JEM-2000FX 200 keV Transmission Electron Microscope (TEM) with STEM electronics, high resolution video system, side entry goniometer, and quick change specimen holder (3.4 Å resolution).

JEOL JSM-5200 Scanning Electron Microscope (SEM) with backscattered electron detector and Energy Dispersive X-Ray (EDX) analysis. Magnification range 15×-200,000× (55 Å resolution).

Diamond saw, polisher, dimpler, jet thinner, ion mill, etc. for preparation of specimens for electron microscopy.

Fully equipped darkroom including 4″×5″ enlarger, archival film and print washers, film and print driers, etc. for processing and printing x-ray film and electron micrographs.

Both electron microscopes and associated equipment were obtained with funding from the AFOSR University Research Initiative Program

Scanning Probe Microscopies (STM and AFM)

An Omicron atomic resolution UHV AFM/STM as part of one of the group’s three MBE machine.

Digital Instruments Nanoscope II Scanning Tunneling Microscope (STM) for surface measurements and epitaxy studies with atomic resolution.

WYKO MicroProbe 3D Atomic Force Microscope (AFM) for surface measurements and epitaxy studies of metals and insulators with atomic resolution.

Optical Microscopes

Zeiss Universal R research microscope on a vibration isolation table with 10× through 100× brightfield/darkfield objectives. Also, a Mirau interferometer for thickness measurements to an absolute precision of ±0.3% (for a 1 µm film), and digital, 35mm and 4″×5″ photomicroscopy equipment.

Olympus BH-2 metallurgical microscope with 10× through 100× Nomarski interference contrast and brightfield/darkfield objectives and a color CCD camera, as well as and digital, 35mm and 4″×5″ photomicroscopy equipment.

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MEASUREMENT OF PHYSICAL PROPERTIES

in situ, ultra-high vacuum

As part of the analytical capabilities of our three MBE machines: Auger spectroscopy, angle-resolved X-Ray Photoelectron Spectroscopy (XPS/ESCA), and Ion Scattering Spectroscopy (ISS) at temperatures to 800 oC; Reflected High and Low Energy Electron Diffraction (RHEED and LEED) to 1100 oC; Secondary Ion Mass Spectroscopy (SIMS); and atomic resolution scanning probe microscopies (AFM and STM). Also, in situ Brillouin light scattering and Surface Magneto-Optic Kerr Effect (SMOKE) apparatus for magnetic studies to 3 kGauss with sub-monolayer sensitivity of ultra-thin films and surfaces under UHV conditions.

ex situ

Computer-controlled ex situ Surface Magneto-Optic Kerr Effect (SMOKE) with field strength to 15 kGauss.

Sandercock six-pass tandem Fabry-Perot interferometer with 200 mW, 532 nm frequency-doubled, diode-pumped, Nd YAG laser. The system was obtained with funding from the AFOSR Defense University Research Instrumentation Program. (DURIP).

Beckman-Coulter DU-640 UV/Vis/IR Spectrophotometer modified for measuring the optical properties of thin films, in transmission and reflection, over the wavelength range 190-1100 nm.

Digital Measurement Systems model 880 Vibrating Sample Magnetometer (VSM) with field strength to 13.5 kGauss, and variable temperature from 77 K-400 oC for studies of magnetic properties of thin films [joint with Prof. Mansuripur’s group in the Optical Sciences Center].

3He cryostat with 6 T superconducting solenoid, for electrical transport properties measurements in the range 0.3-1.2 K.

10’w × 14’d × 10’h shielded room with pumping lines and four cryostats, including one with mu-metal shielding, for low noise-level measurements in the range 0.3-4.2 K. Equipment also includes several SQUID magnetometers with associated electronics, temperature controllers, lock-in amplifiers, electronics for tunneling measurements, etc.

Precision electrical transport properties measurement system based on a closed-cycle refrigerator, IBM PC, and various IEEE-488 instruments (nanovoltmeter, electrometer, lock-in amplifier, digital voltmeter with multiplexer, etc.) to measure resistivity in the range 7.5-300 K with 6½ digit accuracy, as well as thermopower and magnetoresistance.

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GENERAL SUPPORT FACILITIES

Computational | Fabrication Equipment

Computational

Our group has a large number of microcomputers, various types of dedicated data acquisition boards, scanners, digitizing tablet, laser printers, and several types of plotters. All of these microcomputers are networked with the university’s mainframes. Scientific software includes several computer codes for designing multilayer thin films, including effects of roughness and imperfections, and for automatically optimizing the design of x-ray optical coatings using variable layer spacings. Some of these design programs run on our microcomputers, and others on the university’s mainframes. Other scientific software include a search/match package with a complete set of ICDD files on CD-ROM for identifying measured x-ray diffraction spectra, a search/match package from NIST for chemical state identification from XPS data, image analysis software for LEED and RHEED patterns, and codes for simulating x-ray powder diffraction patterns, surface and overlayer structures, and LEED spectra.

Fabrication Equipment

For specialized mechanical fabrication work our group has its own shop with a Bridgeport mill, South Bend lathe, Clausing bandsaw, drill press, bench grinder, belt sander, acetylene and oxy-hydrogen torches, TIG and MIG welders, plasma cutter, sandblasting cabinet, 12-ton hydraulic press, diamond saw and wet sander for preparing special substrates, etc.

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