Three Layer 1.3 μm InGaAsP DH Laser with Quaternary Confining Layers

Abstract

Improvements in the surface morphology of the InGaAsP (DH) laser system were obtained by the addition of small amounts of Ga and As in the confining layers. This method is very promising as a simple and reproducible way to produce high quality wafers giving a very high yield of devices with low threshold current density. The importance of good morphology at the active layer interfaces in reducing optical scattering losses, consequently in reducing threshold current scatter and improving device yield has been demonstrated for GaAs/GaAlAs lasers (1–2–3). The binary InP confining layer typically has poor morphology mainly due to a slight misorientation of the substrate and phosphorous loss. The use of quaternary buffer layer resolves both these problems without recourse to extreme care in crystal orientation and some special means of increasing phosphorous partial pressure near the substrate location.