EFFICIENCY OF PHOTOLUMINESCENCE AND EXCESS CARRIER CONFINEMENT IN INGAASP GAAS STRUCTURES PREPARED BY METAL-ORGANIC CHEMICAL-VAPOR-DEPOSITION/

Special double and separate-confinement InGaASP/GaAs heterostructures intended for photoluminescence measurements have been grown by low-pre ssure metal-organic chemical-vapor deposition. The band gap of the act ive region quaternary material was close to 1.5 ev, and the waveguide of the separate-confinement structures was near 1.8 eV. Measurement of the integrated luminescence efficiency at 300 K has shown that over a wide range of excitation level (10-10(3) W/cm2) radiative transitions are the dominant mechanism for excess carrier recombination in the ac tive region of the structures studied. As determined by spectral measu rements, the excess carrier concentration in the waveguide of the sepa rate-confinement heterostructures and the intensity of the waveguide e mission band correspond to a condition of thermal equilibrium of the e xcess carrier populations in the active region and the waveguide. The ratio of the intensity of the waveguide emission to the active region emission fits a model which assumes that the barrier height for minori ty carriers (holes) is equal to the difference in band gaps between th e active region and the waveguide region.