Analysis of leakage current in GaAs/AlGaAs buried-heterostructure lasers with a semi-insulating GaInP:Fe burying layer

The leakage current in recently demonstrated GaAs/AlGaAs buried heterostructure (BH) lasers with a semi-insulating (SI) GaInP:Fe burying layer has been theoretically and experimentally analyzed. Calculated current-voltage characteristics of n-GaAs/SI-GaInP/n-GaAs and p-GaAs/SI-GaInP/p-GaAs planar configurations have been studied specially to assess the behavior of SI-GaInP:Fe under electron and hole injection. Two-dimensional potential profiles have been used to explain the leakage current mechanism in the SI-GaInP-buried lasers. Simulations reveal that the total leakage current decreases as the active trap concentration in the SI-GaInP:Fe burying layer is increased as expected, but the leakage current is strongly confined in the vicinity of the active region where the local leakage current density increases significantly as the trap density increases. It is found that the insertion of a n-GaInP hole blocking layer between the p-metal and the SI-GaInP layer decreases the total leakage current. Experimental light-current and current-voltage characteristics of fabricated lasers with and without an additional n-GaInP layer, and electroluminescence (EL) emitted from the burying GaInP:Fe layers corroborate qualitatively the simulations and demonstrate the benefits of using a n-GaInP layer for reducing leakage current in these type of lasers. (C) 2002 American Institute of Physics.