EXCITONS IN CONFINED SYSTEMS - FROM QUANTUM-WELL TO BULK BEHAVIOR

A theoretical study of excitons in CuCl films is presented, which is valid for both L approximately a(B) and L much greater than a(B), where L is the well width and a(B) is the exciton radius. Exciton binding energies and oscillator strengths are calculated, and the effect of the different dielectric constant of the barrier is studied in detail. The oscillator strength as a function of wen width is shown to have a minimum at L approximately 3a(B). The radiative lifetime of free excitons is calculated. For thin wells, thermalization produces a radiative lifetime which is linear in temperature. For wide wells, the lifetime becomes independent of well width and proportional to T3/2.