Epitaxial film growth and characterization

Abstract

This chapter reviews the current status of epitaxial growth technology and the characterization of the deposited material. The production of cutting edge compound semiconductor devices requires the growth of high quality epitaxial layers. An epitaxial layer is one that takes the same structure as the substrate it is deposited on—that is, the same crystal symmetry and lattice constant. If the layer is the same material as the substrate, it is said to be homoepitaxial, and if the layer is a different material, it is heteroepitaxial. Other derivatives include strained-layer epitaxy, where elastically strained layers of different lattice constant also exist. The two principal techniques in widespread use today for the deposition of compound semiconductor materials are molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD). MOCVD is a broader term that is applicable to the deposition of crystal, polycrystalline, and amorphous materials. Both MBE and MOCVD have produced a wide range of very high-purity semiconductor materials with excellent optical and electrical properties. Most research and development has centered on the growth of III–V semiconductor binary, ternary, and quaternary alloys with greatest emphasis on GaAs, (AlGa)As, and (GaIn)As.