Surface exciton formation on InP(110)-(1 x 1) studied by time- and angle-resolved photoemission spectroscopy

Using time-and angle-resolved photoemission spectroscopy, we study the surface exciton formed on InP(110)-(1 x 1) surface at 90 K under ultrahigh vacuum conditions. The surface exciton shows a characteristic photoemission peak with a long lifetime of 9.5 ns at 90 K. The exciton binding energy is 28 meV, about 5.5 times larger than the energy of bulk excitons. The radial probability density at the lowest state of the exciton is spheroidal, confined within X6 angstrom from the surface along the surface-normal direction with a radial spread of X44 angstrom in the plane parallel to the surface, being a quasi-two-dimensional excitonic state. These features are consistently described in terms of the exciton theory based on the Wannier equation. Both the reduced screening effects and the two-dimensional confinement at the surface region play important roles in charactering the surface exciton on InP(110)-(1 x 1) surfaces.

Automated summary

Using time-and angle-resolved photoemission spectroscopy, the characteristics of surface exciton on InP(110)-(1 x 1) surface at 90 K under ultrahigh vacuum conditions were studied. The surface exciton exhibited a characteristic photoemission peak with a long lifetime of 9.5 ns at 90 K. The exciton binding energy was 28 meV, significantly larger than bulk excitons. The radial probability density of the exciton was spheroidal, confined within X6 angstrom from the surface along the surface-normal direction with a radial spread of X44 angstrom in the plane parallel to the surface, indicating a quasi-two-dimensional excitonic state. These findings were consistently described by the exciton theory based on the Wannier equation. The reduced screening effects and two-dimensional confinement at the surface region played important roles in characterizing the surface exciton on InP(110)-(1 x 1) surfaces.