Strain Balanced InGaAs/GaAsP Multiple Quantum Well Modulators at 1.06 µm

Abstract

We review growth and optical properties of strain balanced, InGaAs/GaAsP Multiple Quantum Well structures on GaAs in order to make defect free, 1.06 µm modulators. Here, we implement strain balancing near the elastic limit on a length scale of strong size quantization so as to open up a special class of semiconductors materials. In this system we find the in-plane electron mass is strain-enhanced by 30 %. This preserves both excitonic binding energy and excitonic oscillator strength. Consequently, quantum well absorption at 1.06 pan can be nearly comparable to that of a GaAs qw. Also, strain balanced materials show an improved capacity over 850 nm MQW to optically modulate light signals through the Quantum Confined Stark Effect. This is attributed to a light -heavy hole splitting of 140 meV that is caused by a large component of shear strain in these systems. Growth of strain balanced materials is challenging because the strain energy can be comparable to the surface energy that bonds atoms to the crystal. In order to accurately predict the critical layer thicknesses for strain relief as well as the reorganized surface topology, we develop a 2D-3D growth mode model.