Material Growth of InGaAs/InAlAs Superlattices for Quantum Cascade Laser Application

Abstract

Quantum Cascade Lasers (QCLs) have rapidly advanced to a leading position among infrared light sources, and are being used in a number of chemical sensing and spectroscopic applications. Most of these devices are grown by molecular beam epitaxy (MBE) except for some of those grown by metalorganic chemical vapor deposition (MOCVD). This thesis investigates the material growth of near-infrared (NIR) QCLs of InGaAs/InAlAs lattice-matched system using MOCVD. The effects of various growth parameters were understood by detailed study on the material properties of InGaAs and InAlAs. Also, in-depth study on InGaAs/InAlAs superlattices shows that there exists a growth window to optimize their performance. With proper interruption periods of growth between individual layers, the hetero-interfacial defects can be reduced at high growth temperature without surface degradation of constituent layers. Finally, the preliminary study of NIR QCLs with digital alloys insertion was conducted and some QCLs wafers were grown successfully.