The effects of strain on intrasubband scattering rates in InP-based strained-layer quantum-well lasers

Abstract

We analyze the strain effects (both compressive and tensile) on the intrasubband scattering rates for electrons and holes in InP-based strained-layer quantum-well (SL-QW) lasers. Carrier-carrier and carrier-LO-phonon interactions are taken into account on an equal basis within the fully dynamic random phase approximation for multi-subband structures at finite temperatures. The principal influences of the strain-induced changes in the valence band structures on the scattering rates are discussed in terms of the changes in the valence-band density of states and the phonon coupling with holes. We show that the hole-hole interaction plays a dominant role in determining the hole scattering rates regardless of the carrier energy. On the other hand, for electron scattering rates, the dominant scattering mechanism switches from electron-hole interaction to electron-electron interaction as the initial energy of electron increases. We also demonstrate that it is essential to take into account the mutual interactions among the individual scattering processes, such as carrier-carrier scattering and carrier-LO-phonon scattering, when evaluating the intrasubband scattering rates in SL-QW lasers.