Abstract

We propose a new physical approach to design mid-IR lasers based on III-V compounds operating in the spectral range 3-4µm. The using of the wide-gap confined layers with large band offsete at the narrow-gap active layer heteroboundaries allows to create the high barriers for carriers and to reduce leakage current from an active region, that leads to increase the quantum efficiency of the emission due to the strong accumulation of the recombining carriers. Theoretical model of a new asymmetric laser combining the advantages of type I and type II heterostructures will be discussed. Here this approach was successfully used for fabrication of the high power lasers operating at λ=3.26µm. The laser structure containing the narrow-gap active InGaAsSb (Eg=0.380eV) layer sandwiched by the wide-gap InAsSbP (Eg=0.520eV) and GaInAsSb (Eg=0.640eV) layers lattice-matched to InAs substrate was grown by liquid phase epitaxy. Such heterostructure has the band energy diagram of the type II heterostructure with strong asymmetric band offset confinement at the interface that allows to provide high barriers for electrons at the InGaAsSb/GaInAsSb heteroboundary (ΔE_c=0.60eV) and for holes at the InGaAsSb/InAsSbP one (ΔEv=0.15eV) [1].

© 2000 IEEE