ABSTRACT
This chapter reviews some of the important aspects of surfaces and their chemical considerations, as they apply to heteroepitaxy. It discusses several aspects of quantum dot fabrication, including self-assembly, self-organization, and precision placement. The surface of a semiconductor substrate will generally take on a structure different from that of a truncated bulk crystal. Surfactants, or surface-segregated impurities, have a number of applications in heteroepitaxy and engineered heterostructures. Heteroepitaxy usually involves the creation of an interface between semiconductor crystals having different ionicities. An important difference between homoepitaxy and heteroepitaxy is that heteroepitaxy requires nucleation of a new phase on the substrate surface. Heterogeneous nucleation takes place in the presence of a surface and is more relevant to the case of heteroepitaxy. The macroscopic model for heterogeneous nucleation is based on macroscopic properties such as the surface and interfacial free energies. Nucleation layers of AlN are commonly used in the heteroepitaxy of nitride semiconductors on sapphire substrates.
