Quantum-size effects on the pressure-induced direct-to-indirect band-gap transition in InP quantum dots

We predict that the difference in quantum confinement energies of Gamma-like and X-like conduction states in a covalent quantum dot will cause the direct-to-indirect transition to occur at substantially lower pressure than in the bulk material. Furthermore, the first-order transition in the bulk is predicted to become, for certain dot sizes, a second-order transition. Measurements of the "anticrossing gap" could thus be used to obtain unique information on the Gamma-X-L intervalley coupling, predicted here to be surprisingly large (50-100 meV).