Manipulating the Epitaxial Growth of Highly Lattice - Iii-V Semiconductors: Indium Arsenide and its Alloys on Gallium Arsenide Substrates

The inability to grow high-quality epitaxial films which are lattice-mismatched to the starting substrate limits the semiconductor materials available for commercial and device physics applications. This work describes how the kinetic pathways of nucleation, growth, and strain relaxation may be manipulated to alter the surface morphology and defect structure of highly-strained layers. The evolution of InAs islands on (100) and (111)B GaAs substrates has been investigated by varying growth parameters during metalorganic chemical vapor deposition. Island geometry, InAs nucleus saturation density, and the influence of AsH_3 flow on cluster density are markedly different on the two orientations. This work demonstrates that a two-species (anion + cation) nucleation theory is required for a more complete description of III -V semiconductor epitaxy. It is then shown that epitaxial growth can be manipulated for two very different types of device applications. An approach to adjusting the dimensions of InAs islands for low dimensional, as-grown nanostructures is presented. Moreover, controlled registration of InAs clusters and selective -area growth of III-V thin-films on GaAs substrates is achieved via a novel combined high dose electron beam lithography/epitaxial growth technique. Planar InAs films can also be grown on both substrate orientations by altering the growth conditions. By exploiting the advantageous nature of the initial islands on (111)B GaAs substrates, we have produced atomically terraced, fully relaxed InAs films with misfit dislocations confined to the epilayer/substrate interface. Finally, a general multi-step approach for creating high quality lattice-mismatched active regions is discussed.