Two-dimensional exciton
= Two-dimensional exciton
In the ideal screened-Coulomb model confined to a plane, the relative-motion energies are $-R^*/(\nu-1/2)^2$ for $\nu=1,2,\ldots$, where $R^*=(\mu/m_e)13.6\,\mathrm{eV}/\varepsilon_r^2$. The ground-state binding is $4R^*$ rather than the three-dimensional value $R^*$. Finite-width wells need not be exactly planar.