Molecular Beam Epitaxy (MBE) is an ultra high vacuum (UHV) crystal growth technique offering the ability to control material composition down to the atomic layer level. The UHV allows monitoring of crystal growth and quality using Reflective High Energy Electron Diffraction (RHEED) in real time. Molecular Beams are generated and controlled by heating of source materials in dedicated Knudsen cells and substrates being grown on also have their temperature carefully controlled for optimum quality of grown material.
The MBE run by the solar group at the University of Delaware is a state of the art GenIII Veeco system. The materials that can be grown in the system are a part of the technologically important III-V semiconductors and include GaAs, GaSb, InAs, InP as well ternary (or even quaternary) combinations of these binary alloys. By suitable growth of combinations fo these materials nanostructure devices such as quantum wells and quantum dots are grown. Combined with electrical and optical characterization facilities at the University of Delaware research into the behavior of such nanostructures is investigated with particular emphasis on their potential uses in high efficiency solar cells.