Abstract
In the effective-mass approximation, the mass of an exciton is just the sum of the electron and hole masses, . However, the effective-mass approximation is invalid if the forces are strong. Here we derive a plausible formula for the th bound state of the exciton: , where is the kinetic energy in the bound state and is one-half the sum of the electron and hole bandwidths. For Wannier excitons, , while for Frenkel excitons, , and the composite particle is effectively localized.
- Received 12 July 1984
DOI:https://doi.org/10.1103/PhysRevLett.53.1391
©1984 American Physical Society