Gallium Arsenide/indium(x) ALUMINUM(1-X) Arsenide Heterostructure (0 < X < 3): Band Offset and Tensile-Strained Quantum Wells.

Strain built up from the lattice-mismatched heterostructure has a significant influence on the valence-band structure of the strained constituent material. For an unstrained or compressive-strained quantum well, the top valence band is always the heavy hole. The top valence band of a tensile -strained quantum well can be the light hole or heavy hole, depending on the strain and confinement effects. The photon polarization of the in-plane optical transition is different for the electron-heavy hole and electron-light hole transitions. Therefore, the polarization-insensitive interband transition from a quantum well can be realized with the inclusion of tensile strain. In this dissertation, Raman and PL measurements of the GaAs/In_{x}Al_ {1-x}As tensile-strained heterostructure is reported. The X-band gap of the bulk rm In_{x}Al_{1-x}As (0 < x < 0.3) was also measured from low-temperature photoluminescence for the use of band offset measurements. (GaAs/rm In_{x}Al_{1-x}As (x = 0.07 and 0.1) tensile-strained quantum wells were grown on the (001) GaAs substrate using molecular-beam epitaxy. The incorporation of tensile strain is made possible by preparing a 1 μm thick rm In_{x}Al_{1-x}As relaxed buffer which is followed by the growth of quantum wells. An iterative analysis is developed to determine the GaAs/rm In_{x}Al _{1-x}As valence-band offset from the type-I and type-II transitions of the quantum well. The measured valence-band offset is compared with the prediction of the model-solid theory. Strain of GaAs is also measured from Raman spectroscopy and photoluminescence. The photoluminescence measurements from the 25 A well to the 100 A well reveal that the observed optical transition originates from the electron-light hole recombination for a 100 A well and from the electron-heavy hole recombination if the well thickness is less than 40 A. This shows that tensile strain, obtained from the deposition of a thick rm In_{x}Al_{1-x}As buffer, is useful to tune the relative energy position of the light and heavy holes for GaAs-based quantum wells.