Enhanced exciton absorption and saturation limit in strained InGaAs/InP quantum wells

A new approach for enhancing the exciton absorption and increasing the saturation limit in quantum wells (QWs), using tensile strain, is proposed. Because of the valence-band mixing in a strained QW, the in-plane hole mass can become very large or negative. This leads to a heavy electron-hole reduced mass (exciton mass), and therefore to a small exciton radius. Exciton absorption is substantially increased because of the increased electron-hole overlap probability in these small-radius excitons. The effects of saturation are also substantially reduced because of decreased charge-screening effects for small-radius excitons and because the rapid dispersal of the photon-generated excitons reduces the Pauli exclusion effect.