| III-V semiconductors with the lattice spacing of 6.1A---GaSb, AlSb, InAs, and their heterostructures---offer great flexibility in designing novel solid-state devices via bandgap engineering. Despite of increasing interest, optical properties of these materials are still not well understood. In order to design and optimize device structures, knowledge of optical properties over a wide energy range is of importance. In this study, dielectric responses of AlxGa1- xSb (0.00 ≤ x ≤ 0.39) alloys, (GaSb) 3n(AlSb)n (1 ≤ n ≤ 5) superlattices, and InAsxP1-x (0.0 ≤ x ≤ 1.0) alloys have been determined by spectroscopic ellipsometry. Analysis of second-energy-derivatives calculated numerically from the measured data yielded the critical-point energies of the E1, E1+Delta1, E0', E2, and E 1' for both AlxGa1- xSb alloys and (GaSb)3n(AlSb) n superlattices while the E1, E1+Delta1, E0', E2, and E2+delta for InAs xP1-x alloys. Dependences of the critical-point energies on alloy composition and superlattice period have been obtained for the alloys and the superlattices, respectively. For the superlattice samples, two additional features were also observed near the E1+Delta1 critical-point structures for n ≥ 4.; There is increasing interest in semimetallic rare-earth group-V compounds integrated into III-V semiconductor for potential applications in metal-base electronic devices, thermodynamically stable metallic contacts, and novel optoelectronic devices based on metallic nanoparticles. We have studied Sc xEr1-xSb compounds that grow epitaxially on the 6.1A family of III-V semiconductors. For the success of epitaxial growth of dissimilar materials, the ability of tailoring surfaces and interfaces on the atomic scale is required. This research focus, therefore, has been on understanding the initial growth nature of ErSb on GaSb(100). Results show that the initial nucleation of ErSb on GaSb(100) surfaces produces nanometer scale islands embedded within the surface of the GaSb. The growth is well represented by the embedded growth model in which islands nucleate in the surface of a substrate, grow laterally, and coalesce into a uniform film, and continue to grow in a layer-by-layer mode. |
