ADVANCES IN MOLECULAR-BEAM EPITAXY (MBE)

Molecular beam epitaxy (MBE) continues to set the standard for the control of epitaxial layer thickness and uniformity over a large substrate area. Recent improvement in growth conditions allow us to prepare epitaxial materials free from oval defects with electrical and optical properties better than or as good as any other crystal growth technique. Artificially structured materials permit us to explore physical and chemical properties that do not exist in nature. In the area of crystal growth, there have been two main movements in recent years: one is to grow in selective areas by depositing on patterned substrates or with focussed ion beams; the other is to extend epitaxial growth beyond lattice-matched systems with strained layers. Alloy systems such as Al(x)Ga(y)In1-x-yAs, Al(x)Ga1-xAs(y)Sb1-y, InAs(x)Sb1-x, Ga(x)In1-xP, SiGe, ZnSe, and CdZnTe/ZnTe are among the new materials explored. New devices grown by MBE with exciting results are surface emitting lasers, strained quantum well lasers, quantum well infrared photodetectors, and real-space transfer heterostructure transistors (NERFETs). This paper will review recent advances in the conventional solid source MBE.