Greene Lab - Facilities

Our research involves a variety of activities ranging from sample preparation, measurement to data analysis. Samples are typically in either thin film or single crystalline form. Thin films are grown by sputtering or evaporation techniques in vacuum deposition systems. Single crystalline samples oftentimes need to be polished to mirror-like shininess for measurements or further processing, for which optical microscopes are used. More sophisticated devices like a tunnel junction are also prepared on these samples using lithographic techniques. As our research concerns about electron spectroscopic properties, two major techniques are employed: quasiparticle scattering spectroscopy (or point-contact spectroscopy) and planar tunneling spectroscopy. For these measurements, various probes and instrument setups are available to be used with cryostats for controlling the temperature and magnetic field.

Cryostats

The physical properties of samples and devices are measured in a cryostat for the control of sample temperature and the application of magnetic field.

Measurement Instruments

Measurement setups are available in three separate instrument racks. For conductance measurement, they are equipped with a custom-built mixing circuit, two lock-in amplifiers, a current source, and digital multimeters (or DAQ boards).

Optical Microscopes

Optical microscopes are used for wiring on a sample, aligning a tip with a sample in PCS, and detailed inspection of a sample surface.

PCS Probes

Three different types of probes are available for point contact spectroscopy (PCS). The major difference is how to move the tip towards or away from the sample.

Thin Film Deposition Systems

Thin film samples and devices are prepared using vacuum deposition techniques including sputtering and evaporation. Sputtering is a technique to detach atomic species from the target surface via momentum transfer due to ionized inert gases (typically Ar). Those species landing on a substrate can form a thin layer on a substrate. On the other hand, evaporation techniques rely on melting and vaporization of a heated source material.