Facilites

The different facilities, equipment and other resources available in the group are:

For sample preparation and fabrication:

  • Multi-target RF/DC magnetron sputtering system
  • Pulsed laser deposition (PLD) system equipped with ion-beam-assisted deposition (IBAD) unit
  • Metal-organic chemical vapor deposition system (MOCVD)
  • Thermal evaporation system
  • Electron beam sputtering system
  • Various one-zone and three-zone furnaces
  • Two dry nitrogen glove box, one with environmental control

For sample and device characterization:

  • X-ray diffractometer
  • Oxford closed cycle cryostat (10-400K) with optical windows (UV-Far IR) for optical and electrical transport measurements
  • SQUID magnetometer (7 Tesla, 4.2 K-400 K)
  • Superconducting magnet system (10 Tesla, 1.2K-300K)
  • Field-emission scanning electron microscopy with energy dispersive x-ray spectroscopy and electron backscattering Kiguchi pattern (SEM/EDS/EBKP). This FESEM is also equipped with electron beam lithography system (shared system).
  • Scanning transmission electron microscopy with EDS (STEM/EDS)
  • Deep UV photo lithography system (shared system)
  • Variable temperature ellipsometer
  • Various electronics and data acquisition systems for dc and ac electrical transport measurements
  • Microwave source, amplifier and analyzers in 50M-40 GHz including HP 8722 microwave spectrum analyzer, AR5S1G4 amplifier, and various microwave probes and resonator cavities (Nb and Cu)
  • Near-field microwave and optical scanning dual-probe microscopy
  • Optical Microscopes

Scanning Electron Microscope

Optical and Microwave Dual Probe Set Up

Ion Beam Assisted e-beam Deposition System

Our in house Ion Beam Assisted e-beam Deposition system (IBAD e-beam) system allows for the study and fabrication of bi-axially textured films. The IBAD system is equipped with two electron beam evaporators. One is a 4 pocket e-beam evaporator which can deliver currents of up to 600 mA at a voltage of about 10KV. The multi-pocket configuration allows for different materials to be evaporated in sequence without breaking the vacuum during deposition of multi-layered structures. Another e-beam evaporator can be used for co-evaporation of two different materials. The atomic deposition rate can be monitored in situ by a quartz crystal thickness monitor, which is located near the substrate holder. For IBAD applications, the system is equipped with a 3 cm. Commonwealth Scientific Kauffman type ion gun, capable of accelerating voltages up to 1500 V and ion beam currents up to 70 mA. The angle between the ion gun axis and substrate normal can be varied depending on the desired ion bombardment angle. The ion current density at the substrate is measured by a movable Faraday cup. In order to monitor in situ the texture development of the growing IBAD films, a STAIB RH 35 Reflection High Energy Electron Diffraction (RHEED) system is also installed, operating at about 35 keV. The RHEED diffraction pattern is reflected to an 8" phosphor screen, with the diffraction patterns captured by a CCD camera. A KSA RHEED control software is also installed for the control and data acquisition of RHEED patterns. For temperature control of the substrate during deposition, a temperature controller is utilized to vary the substrate temperature, which can deliver temperatures of up to 9500 C at the substrate holder.

UHV SPM Head and Controller

Our UHV-SPM scan head is capable of STM and AFM measurements of atomic resolution in vacuum. It possesses a maximum scan range of 5um and uses a stick-slip method of sample approach. The SPM32 controller, manufactured by RHK Technologies is capable of controlling many different styles of piezo including our home-built STM/NSOM dual probe SPM.

Thermal Evaporator

Our thermal evaporator uses DC heating of a tungsten filament to evaporate material onto a sample. It is equiped with a shutter for precise exposure times, and there is a quartz crystal monitor ready to install for calibration of this instrument.

Electron Beam Sputtering System

The magnetron electron beam sputtering system operates at ~70 mTorr and 0.05 mA beam current with a potential of several hundred volts. It is useful for despositing a uniform thin film of target material onto a sample. Targets include silver, copper and gold.

Pulsed Laser Deposition (PLD) System

The Pulsed Laser Deposition system is equipped with a Lambda Physik excimer laser with variable power output (up to 50 Watts), which is used to ablate the desired deposition material. The deposition chamber has a computer controlled, rotating target holder accommodating rapid multilayer film growth. The system also features a Kauffman type ion gun, making ion assisted depositions possible.

X-Ray Diffractor

The Bruker-AXS D8 x-ray diffractometer is a shared resource of the KU Crystallography Lab.  The diffractometer produces a focused x-ray beam that may be scattered from the material under study, and the interference patterns provide information about the crystal structure of the sample (such as a thin film).  The instrument is capable of measurements of out-of-plane structure (theta-2theta scan), as well as in-plane structure (phi scan).

SQUID

The SQUID (Superconducting Quantum Interference Device) is the magnetic property measurement system made by Quantum Design. Superconductivity can be studied by  measuring the magnetic response of the material using the SQUID.

Electronics For Superconducting Transport Measurement

We have three probes for the transport system which enables us to determine the transport properties of HTS materials. We have an HP nanovoltmeter, Keithley 224 Programmable current source, 2 matrix boxes for connecting HTS samples to electronic instruments, pulsed I-V system for high Ic measurements, and Lakeshore 330 and 331 temperature controllers. We are capable of measuring Jc and RT in field of up to 5 Tesla using the SQUID magnetometer.

Resources Available from Collaboration

Many other facilities and resources are available and accessible through the collaboration. These include: high-energy ion-beam for RBS/channeling analysis, XRD pole figures, Auger spectroscopy, HRTEM, AFM/STM, microwave (surface resistance measurement of Hg-HTS films and power-dependence of prototype devices). All these facilities are free of charge to the proposed research.