SPONTANEOUS EMISSION FROM EXCITONS IN THIN DIELECTRIC LAYERS

Spontaneous emission from quantum-well excitons in a thin, high-refrac tive-index dielectric layer embedded in a low-refractive-index bulk di electric is studied as a function of the layer thickness and refractiv e-index ratio. Total spontaneous emission rates for a thin layer decre ase linearly with the index ratio for dipoles in the plane of the laye r and as the fifth power of the index ratio for dipoles with orientati ons perpendicular to the layer. These results are of interest in the d esign of optical microstructures that control the exciton emission dyn amics of semiconductor quantum wells.