Materials Issues and Device-Degradation in the Ingaas(P)/Inp System

Abstract

ABSTRACTThis paper reviews the current status of material issues in the InGaAs(P)/InP system and our understanding of degradation in InGaAsP/inP double-heterostructure lasers and LED's.Among the materials issues for this system are the generation of defects and the thermal stability of the material. Crystal growth-induced defects can be classified into interface and bulk defects.; the former group includes misfit dislocations and inclusions and the latter structural and non-structural precipitates. Thermal stability can lead to structural imperfections stuch as quasi-periodic modulated structure due to spinodal decomposition of the crystal either at the liquid/solid interface or growth surface, and atomic ordering which also occurs on the growth surface through migration and reconstruction of deposited atoms. Diffusion processes in InP often lead to the generation of microdefects in this material. Finally, in metallization procedures, alloy reactions between the semiconductor and electrode occasionally take place forming non-planar/non-uniform interfaces.Three major degradation modes, rapid degradation, gradual degradation, and catastrophic failure in InGaAsP/InP double-heterostructure lasers and LED's, are discussed. For rapid degradation, recombination-enhanced dislocation climb and glide, which are responsible for degradation, do not occur easily InGaAsP/JnP system. Differences in the ease with which these phenomena occur in InGaAsP/InP and other systems are presented. Based on the results, dominant parameters involved in the phenomena are discussed. Gradual degradation takes place presumably due to recombination enhanced point defect reaction in GaAlAs/GaAs-based optical devices. However, we do not observe this mode in InGaAsP/InP-based optical devices. Catastrophic failure due to catastrophic optical damage at a mirror or at a defect in GaAlAs/GaAs DH lasers, is not found in InGaAsP/lnP DH lasers. Degradation of InGaAsP/InP double-heterostructure LED's with large current application is also presented. These results indicate that InGaAsP/InP optical devices ensure very high reliability in longwavelength communication systems.