Three-Dimensional Confinement in the Conduction Band Structure of InP

Strong quantum confinement in InP is observed to significantly reduce the separation between the direct and indirect conduction band states. The effects of three-dimensional confinement are investigated by tailoring the initial separation between conduction band states using quantum dots (QDs) of different sizes and hydrostatic pressure. Analyses of the QD emission spectra show that the $X_{1c}$ states are lowest in energy at pressures of $\sim 6\mathrm{GPa}$, much lower than in the bulk. The transition to the $X_{1c}$ states can be explained by either a sequence of $\Gamma -L$ and $L-X$ crossings, or by the crossover between strongly coupled $\Gamma$ and $X$ states.