Microphysics Laboratoy: Facility-cluster-tool

Research Facility
MBE Cluster tool system

Function: The Molecular Beam Epitaxy (MBE) Interconnection System is a unique setup developed entirely by the Microphysics Laboratory.

MBE cluster tool system- Click to enlarge

It consists of four interconnected Ultra High Vacuum (UHV) chambers:

One MBE growth chamber
Two analytical chambers
One plasma and metallization chamber

The interconnection of chambers through UHV transfer modules facilitates faster analysis and prevents contamination of grown layers.

The Interconnection System is one of four MBE chambers at the MPL.

Research: This extremely large system has been employed to do several important research projects, such as:

Studies on the MBE growth dynamics
Growth mechanism of II-VI epitaxial materials
in-situ surface analysis
Studies on diamond and diamond-like films

Specifications:

The MBE growth chamber

The MBE growth chamber is fully equipped with eight conventional knudson effusion cells. It contains a continuous feeding Hg cell, which produces a highly stable Hg flux, a mass spectrometer and Reflection of High-Energy Electron Diffraction (RHEED). The flux from the effusion cell can be interrupted with ease using the small shutters available for each effusion cell. The MBE Interconnection System thus makes it possible to fabricate highly sophisticated artificial materials and structures such as:

quantum well structures
superlattices
hetero/homo structures

with abrupt interfaces
with graded interfaces

The main shutter can block the molecular flux from all the effusion cells and is very important during substrate surface preparation before epitaxial growth. The growth in the system is closely monitored by high energy electron diffraction using a 50 keV RHEED gun. The molecular flux is measured by an ion gauge. Photo-assisted MBE growth is performed using an Ar ion laser. Currently, we are in the process of implementing real-time ellipsometry measurement. When implemented, this will give information about the surface roughness, interface formation, and alloy composition.

The analytical chambers

The two analytical chambers provide in-situ surface analysis such as:

X-ray photo emission spectroscopy (XPS)
Ultraviolet photo emission spectroscopy (UPS)
Auger electron spectroscopy (AES)
Electron loss spectroscopy (ELS)
Secondary ion mass spectroscopy (SIMS)

The plasma and metallization chamber

Metal and/or insulating materials can be deposited in the Ultra-High Vacuum (UHV) plasma metallization chamber using thermal evaporation and/or an electron gun. The plasma can also be used to oxidize the surface or to selectively etch certain areas of the sample.

The plasma metallization chamber combines RF etching, E-beam sputtering and high-temperature evaporating of metals. Currently, a carbon source is connected to this chamber to do research on diamond and diamond-like films.

Interconnection of the chambers

The growth and analytical chambers are interconnected through UHV transfer modules. This enables the study of interface properties--such as possible valence band offset and ohmic contacts--as well as the study of a freshly deposited uncontaminated material.

Attachments

Optical characterization tools such as reflection difference (RD) and spectroscopic ellipsometry are used to perform real-time measurement and analysis.